EX-10.5



 Exhibit 10.5 

TENABLE HOLDINGS, INC. 

2018 EMPLOYEE STOCK PURCHASE PLAN 

ADOPTED BY THE BOARD OF DIRECTORS:
JUNE 28, 2018 
 APPROVED BY THE STOCKHOLDERS:
            , 2018 
 IPO DATE:
            , 2018 
  

	1.	GENERAL; PURPOSE. 

 (a)    The
Plan provides a means by which Eligible Employees of the Company and certain Designated Companies may be given an opportunity to purchase shares of Common Stock. The Plan permits the Company to grant a series of Purchase Rights to Eligible Employees
under an Employee Stock Purchase Plan. 
 (b)    The Company, by means of the Plan, seeks to retain the services
of such Employees, to secure and retain the services of new Employees and to provide incentives for such persons to exert maximum efforts for the success of the Company and its Related Corporations and Affiliates. 

(c)    The Plan includes two components: a 423 Component and a Non-423
Component. The Company intends (but makes no undertaking or representation to maintain) the 423 Component to qualify as an Employee Stock Purchase Plan. The provisions of the 423 Component, accordingly, will be construed in a manner that is
consistent with the requirements of Section 423 of the Code. In addition, this Plan authorizes grants of Purchase Rights under the Non-423 Component that do not meet the requirements of an Employee Stock
Purchase Plan. Except as otherwise provided in the Plan or determined by the Board, the Non-423 Component will operate and be administered in the same manner as the 423 Component. In addition, the Company may
make separate Offerings which vary in terms (provided that such terms are not inconsistent with the provisions of the Plan or the requirements of an Employee Stock Purchase Plan), and the Company will designate which Designated Company is
participating in each separate Offering. 
  

	2.	ADMINISTRATION. 

 (a)    The Board will
administer the Plan unless and until the Board delegates administration of the Plan to a Committee or Committees, as provided in Section 2(c). 

(b)    The Board will have the power, subject to, and within the limitations of, the express provisions of the
Plan: 
 (i)    To determine how and when Purchase Rights will be granted and the provisions of each Offering
(which need not be identical). 
 (ii)    To designate from time to time which Related Corporations will be
eligible to participate in the Plan as Designated 423 Corporations or as Designated Non-423 Corporations, which Affiliates may be excluded from participation in the Plan, and which Designated Companies will
participate in each separate Offering (to the extent that the Company makes separate Offerings). 
 (iii)    To
construe and interpret the Plan and Purchase Rights, and to establish, amend and revoke rules and regulations for its administration. The Board, in the exercise of this power, may correct any defect, omission or inconsistency in the Plan, in a
manner and to the extent it deems necessary or expedient to make the Plan fully effective. 







 (iv)    To settle all controversies regarding the Plan and Purchase
Rights granted under the Plan. 
 (v)    To suspend or terminate the Plan at any time as provided in
Section 12. 
 (vi)    To amend the Plan at any time as provided in Section 12. 

(vii)    Generally, to exercise such powers and to perform such acts as it deems necessary or expedient to promote
the best interests of the Company, its Related Corporations, and Affiliates and to carry out the intent that the 423 Component be treated as an Employee Stock Purchase Plan. 

(viii)    To adopt such rules, procedures and sub-plans relating to the
operation and administration of the Plan as are necessary or appropriate under applicable local laws, regulations and procedures to permit or facilitate participation in the Plan by Employees who are foreign nationals or employed or located outside
the United States. Without limiting the generality of, but consistent with, the foregoing, the Board specifically is authorized to adopt rules, procedures, and sub-plans, which, if applicable to a Designated Non-423 Corporation, do not have to comply with the requirements of Section 423 of the Code, regarding, without limitation, eligibility to participate in the Plan, the definition of eligible
“earnings,” handling and making of Contributions, establishment of bank or trust accounts to hold Contributions, payment of interest, conversion of local currency, obligations to pay payroll tax, determination of beneficiary designation
requirements, withholding procedures and handling of share issuances, any of which may vary according to applicable requirements. 

(c)    The Board may delegate some or all of the administration of the Plan to a Committee or Committees. If
administration is delegated to a Committee, the Committee will have, in connection with the administration of the Plan, the powers theretofore possessed by the Board that have been delegated to the Committee, including the power to delegate to a
subcommittee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board will thereafter be to the Committee or subcommittee), subject, however, to such resolutions, not inconsistent with the
provisions of the Plan, as may be adopted from time to time by the Board. Further, to the extent not prohibited by applicable law, the Board or Committee may, from time to time, delegate some or all of its authority under the Plan to other persons
or groups of persons as it deems necessary, appropriate, or advisable under conditions or limitations that it may set at or after the time of the delegation. The Board may retain the authority to concurrently administer the Plan with the Committee
and may, at any time, revest in the Board some or all of the powers previously delegated. Whether or not the Board has delegated administration of the Plan to a Committee, the Board will have the final power to determine all questions of policy and
expediency that may arise in the administration of the Plan. 
 (d)    All determinations, interpretations and
constructions made by the Board in good faith will not be subject to review by any person and will be final, binding and conclusive on all persons. 
  

	3.	SHARES OF COMMON STOCK SUBJECT TO THE PLAN. 


(a)    Subject to the provisions of Section 11(a) relating to Capitalization Adjustments and the following
sentence regarding the Evergreen Increase, the initial number of shares of Common Stock that may be issued under the Plan shall equal 4,000,000 shares of Common Stock (the “Share Reserve”). In addition, the Share Reserve will
automatically increase on January 1st of each year for a period of up to 

  
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ten (10) years, commencing on January 1, 2019 and ending on (and including) January 1, 2028 (each, an “Evergreen Date”), in an amount equal to the
lesser of (i) one and one-half percent (1.5%) of the total number of shares of Capital Stock outstanding on December 31st immediately preceding
the applicable Evergreen Date, and (ii) 8,000,000 shares (the “Evergreen Increase”). Notwithstanding the foregoing, the Board may act prior to the Evergreen Date of a given year to provide that there will be no Evergreen
Increase for such year or that the Evergreen Increase for such year will be a lesser number of shares of Common Stock than would otherwise occur pursuant to the preceding sentence. For the avoidance of doubt, up to the maximum number of shares of
Common Stock reserved under this Section 3(a) may be used to satisfy purchases of Common Stock under the 423 Component and any remaining portion of such maximum number of shares may be used to satisfy purchases of Common Stock under the Non-423 Component. 
 (b)    If any Purchase Right granted under the Plan
terminates without having been exercised in full, the shares of Common Stock not purchased under such Purchase Right will again become available for issuance under the Plan. 

(c)    The stock purchasable under the Plan will be shares of authorized but unissued or reacquired Common Stock,
including shares repurchased by the Company on the open market. 
  

	4.	GRANT OF PURCHASE RIGHTS; OFFERING. 


(a)    The Board may from time to time grant or provide for the grant of Purchase Rights to Eligible Employees under
an Offering (consisting of one or more Purchase Periods) on an Offering Date or Offering Dates selected by the Board. Each Offering will be in such form and will contain such terms and conditions as the Board will deem appropriate, and, with respect
to the 423 Component, will comply with the requirement of Section 423(b)(5) of the Code that all Employees granted Purchase Rights will have the same rights and privileges. The terms and conditions of an Offering shall be incorporated by
reference into the Plan and treated as part of the Plan. The provisions of separate Offerings need not be identical, but each Offering will include (through incorporation of the provisions of this Plan by reference in the Offering Document or
otherwise) the period during which the Offering will be effective, which period will not exceed 27 months beginning with the Offering Date, and the substance of the provisions contained in Sections 5 through 8, inclusive. 

(b)    If a Participant has more than one Purchase Right outstanding under the Plan, unless he or she otherwise
indicates in forms delivered to the Company or a third party designated by the Company (each, a “Company Designee”): (i) each form will apply to all of his or her Purchase Rights under the Plan, and (ii) a Purchase Right
with a lower exercise price (or an earlier-granted Purchase Right, if different Purchase Rights have identical exercise prices) will be exercised to the fullest possible extent before a Purchase Right with a higher exercise price (or a later-granted
Purchase Right if different Purchase Rights have identical exercise prices) will be exercised. 
 (c)    The
Board will have the discretion to structure an Offering so that if the Fair Market Value of a share of Common Stock on the first Trading Day of a new Purchase Period within that Offering is less than or equal to the Fair Market Value of a share of
Common Stock on the Offering Date for that Offering, then (i) that Offering will terminate immediately as of that first Trading Day, and (ii) the Participants in such terminated Offering will be automatically enrolled in a new Offering
beginning on the first Trading Day of such new Purchase Period. 

  
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	5.	ELIGIBILITY. 

 (a)    Purchase Rights may be
granted only to Employees of the Company or, as the Board may designate in accordance with Section 2(b), to Employees of a Related Corporation or an Affiliate. Except as provided in Section 5(b) or as required by applicable law, an
Employee will not be eligible to be granted Purchase Rights unless, on the Offering Date, the Employee has been in the employ of the Company, a Related Corporation or an Affiliate, as the case may be, for such continuous period preceding such
Offering Date as the Board may require, but in no event will the required period of continuous employment be equal to or greater than two years. In addition, the Board may provide that no Employee will be eligible to be granted Purchase Rights under
the Plan unless, on the Offering Date, such Employee’s customary employment with the Company, the Related Corporation, or the Affiliate, as applicable, is more than 20 hours per week and more than five months per calendar year or such other
criteria as the Board may determine consistent with Section 423 of the Code with respect to the 423 Component and applicable laws. 

(b)    The Board may provide that each person who, during the course of an Offering, first becomes an Eligible
Employee will, on a date or dates specified in the Offering which coincides with the day on which such person becomes an Eligible Employee or which occurs thereafter, receive a Purchase Right under that Offering, which Purchase Right will thereafter
be deemed to be a part of that Offering. Such Purchase Right will have the same characteristics as any Purchase Rights originally granted under that Offering, as described herein, except that: 

(i)    the date on which such Purchase Right is granted will be the “Offering Date” of such Purchase
Right for all purposes, including determination of the exercise price of such Purchase Right; 
 (ii)    the
period of the Offering with respect to such Purchase Right will begin on its Offering Date and end coincident with the end of such Offering; and 

(iii)    the Board may provide that if such person first becomes an Eligible Employee within a specified period of
time before the end of the Offering, he or she will not receive any Purchase Right under that Offering. 

(c)    No Employee will be eligible for the grant of any Purchase Rights if, immediately after any such Purchase
Rights are granted, such Employee owns stock possessing five percent or more of the total combined voting power or value of all classes of stock of the Company or of any Related Corporation. For purposes of this Section 5(c), the rules of
Section 424(d) of the Code will apply in determining the stock ownership of any Employee, and stock which such Employee may purchase under all outstanding Purchase Rights and options will be treated as stock owned by such Employee. 

(d)    As specified by Section 423(b)(8) of the Code, an Eligible Employee may be granted Purchase Rights only
if such Purchase Rights, together with any other rights granted under all Employee Stock Purchase Plans of the Company and any Related Corporations or Affiliates, do not permit such Eligible Employee’s rights to purchase stock of the Company or
any Related Corporation or Affiliates to accrue at a rate which, when aggregated, exceeds US$25,000 of Fair Market Value of such stock (determined at the time such rights are granted, and which, with respect to the Plan, will be determined as of
their respective Offering Dates) for each calendar year in which such rights are outstanding at any time, subject to compliance with applicable laws. 

  
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 (e)    Officers of the Company and any Designated Company, if they are
otherwise Eligible Employees, will be eligible to participate in Offerings under the Plan. Notwithstanding the foregoing, the Board may provide in an Offering that Employees who are highly compensated Employees within the meaning of
Section 423(b)(4)(D) of the Code will not be eligible to participate. 
 (f)    Notwithstanding anything in
this Section 5 to the contrary, in the case of an Offering under the Non-423 Component, an Eligible Employee (or group of Eligible Employees) may be excluded from participation in the Plan or an Offering
if the Board has determined, in its sole discretion, that participation of such Eligible Employee(s) is not advisable or practical for any reason. 
  

	6.	PURCHASE RIGHTS; PURCHASE PRICE. 


(a)    On each Offering Date, each Eligible Employee, pursuant to an Offering made under the Plan, will be granted a
Purchase Right to purchase up to that number of shares of Common Stock (rounded down to the nearest whole share) purchasable either with a percentage or with a maximum dollar amount, as designated by the Board, but in either case not exceeding 15%
of such Employee’s earnings (as defined by the Board in each Offering) during the period that begins on the Offering Date (or such later date as the Board determines for a particular Offering) and ends on the date stated in the Offering, which
date will be no later than the end of the Offering. 
 (b)    The Board will establish one or more Purchase Dates
during an Offering on which Purchase Rights granted for that Offering will be exercised and shares of Common Stock will be purchased in accordance with such Offering. 

(c)    In connection with each Offering made under the Plan, the Board may specify (i) a maximum number of
shares of Common Stock that may be purchased by any Participant on any Purchase Date during such Offering, (ii) a maximum aggregate number of shares of Common Stock that may be purchased by all Participants pursuant to such Offering and/or
(iii) a maximum aggregate number of shares of Common Stock that may be purchased by all Participants on any Purchase Date under the Offering. If the aggregate purchase of shares of Common Stock issuable upon exercise of Purchase Rights granted
under the Offering would exceed any such maximum aggregate number, then, in the absence of any Board action otherwise, a pro rata (based on each Participant’s accumulated Contributions) allocation of the shares of Common Stock (rounded down to
the nearest whole share) available will be made in as nearly a uniform manner as will be practicable and equitable. 

(d)    The purchase price of shares of Common Stock acquired pursuant to Purchase Rights will be not less than the
lesser of: 
 (i)    an amount equal to 85% of the Fair Market Value of the shares of Common Stock on the
Offering Date; or 
 (ii)    an amount equal to 85% of the Fair Market Value of the shares of Common Stock on the
applicable Purchase Date. 
  

	7.	PARTICIPATION; WITHDRAWAL; TERMINATION. 


(a)    An Eligible Employee may elect to authorize payroll deductions as the means of making Contributions by
completing and delivering to the Company or Company Designee, within the time specified in the Offering, an enrollment form provided by the Company or Company Designee. The enrollment form will specify the amount of Contributions not to exceed the
maximum amount specified by the Board. Each Participant’s Contributions will be credited to a bookkeeping account for such Participant under the Plan and will be deposited with the general funds of the Company except where applicable laws or
regulations require that Contributions be deposited with a Company Designee or 

  
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otherwise segregated. If permitted in the Offering, a Participant may begin such Contributions with the first payroll occurring on or after the Offering Date (or, in the case of a payroll date
that occurs after the end of the prior Offering but before the Offering Date of the next new Offering, Contributions from such payroll will be included in the new Offering). If permitted in the Offering, a Participant may thereafter reduce
(including to zero) or increase his or her Contributions. If required under applicable laws or regulations or if specifically provided in the Offering, in addition to or instead of making Contributions by payroll deductions, a Participant may make
Contributions through a payment by cash, check, or wire transfer prior to a Purchase Date, in a manner directed by the Company or a Company Designee. 

(b)    During an Offering, a Participant may cease making Contributions and withdraw from the Offering by
delivering to the Company or a Company Designee a withdrawal form provided by the Company. The Company may impose a deadline before a Purchase Date for withdrawing. Upon such withdrawal, such Participant’s Purchase Right in that Offering will
immediately terminate and the Company will distribute as soon as practicable to such Participant all of his or her accumulated but unused Contributions and such Participant’s Purchase Right in that Offering shall thereupon terminate. A
Participant’s withdrawal from that Offering will have no effect upon his or her eligibility to participate in any other Offerings under the Plan, but such Participant will be required to deliver a new enrollment form to participate in
subsequent Offerings. 
 (c)    Unless otherwise required by applicable law, Purchase Rights granted pursuant to
any Offering under the Plan will terminate immediately if the Participant either (i) is no longer an Employee for any reason or for no reason or (ii) is otherwise no longer eligible to participate. In this regard, unless otherwise
determined by the Board, a Participant whose employment transfers or whose employment terminates with an immediate rehire (with no break in service) by or between the Company and a Designated Company will not be treated as having terminated
employment for purposes of participating in the Plan or an Offering; however, if a Participant transfers from an Offering under the 423 Component to an Offering under the Non-423 Component, the exercise of the
Participant’s Purchase Right will be qualified under the 423 Component only to the extent such exercise complies with Section 423 of the Code. If a Participant transfers from an Offering under the
Non-423 Component to an Offering under the 423 Component, the exercise of the Purchase Right will remain non-qualified under the
Non-423 Component. In the event that a Participant’s Purchase Right is terminated under the Plan, the Company will distribute as soon as practicable to such individual all of his or her accumulated but
unused Contributions. 
 (d)    During a Participant’s lifetime, Purchase Rights will be exercisable only by
such Participant. Purchase Rights are not transferable by a Participant, except by will, by the laws of descent and distribution, or, if permitted by the Company, by a beneficiary designation as described in Section 10. 

(e)    Unless otherwise specified in the Offering or required by applicable law, the Company will have no
obligation to pay interest on Contributions. 
  

	8.	EXERCISE OF PURCHASE RIGHTS. 


(a)    On each Purchase Date, each Participant’s accumulated Contributions will be applied to the purchase of
shares of Common Stock (rounded down to the nearest whole share), up to the maximum number of shares of Common Stock permitted by the Plan and the applicable Offering, at the purchase price specified in the Offering. No fractional shares will be
issued unless specifically provided for in the Offering. 

  
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 (b)    Unless otherwise provided in the Offering, if any amount of
accumulated Contributions remains in a Participant’s account after the purchase of shares of Common Stock and such remaining amount is less than the amount required to purchase one share of Common Stock on the final Purchase Date of an
Offering, then such remaining amount will be held in such Participant’s account for the purchase of shares of Common Stock under the next Offering under the Plan, unless such Participant withdraws from or is not eligible to participate in such
Offering, in which case such amount will be distributed to such Participant after the final Purchase Date, without interest, unless the payment of interest is required by applicable laws. If the amount of Contributions remaining in a
Participant’s account after the purchase of shares of Common Stock is at least equal to the amount required to purchase one whole share of Common Stock on the final Purchase Date of an Offering, then such remaining amount will not roll over to
the next Offering and will instead be distributed in full to such Participant after the final Purchase Date of such Offering without interest, unless the payment of interest is required by applicable laws. 

(c)    No Purchase Rights may be exercised to any extent unless the shares of Common Stock to be issued upon such
exercise under the Plan are covered by an effective registration statement pursuant to the Securities Act and the Plan is in material compliance with all applicable U.S. federal and state, foreign and other securities, exchange control and other
laws applicable to the Plan. If on a Purchase Date the shares of Common Stock are not so registered or the Plan is not in such compliance, no Purchase Rights will be exercised on such Purchase Date, and the Purchase Date will be delayed until the
shares of Common Stock are subject to such an effective registration statement and the Plan is in material compliance, except that the Purchase Date will not be delayed more than 12 months and the Purchase Date will in no event be more than 27
months from the Offering Date. If, on the Purchase Date, as delayed to the maximum extent permissible, the shares of Common Stock are not registered and the Plan is not in material compliance with all applicable laws or regulations, as determined by
the Company in its sole discretion, no Purchase Rights will be exercised and all accumulated but unused Contributions will be distributed as soon as practicable to the Participants without interest, unless the payment of interest is required by
applicable laws. 
  

	9.	COVENANTS OF THE COMPANY. 


The Company will seek to obtain from each U.S. federal or state, foreign or other regulatory commission or agency having jurisdiction over the
Plan such authority as may be required to grant Purchase Rights and issue and sell shares of Common Stock thereunder unless the Company determines, in its sole discretion, that doing so would cause the Company to incur costs that are unreasonable.
If, after commercially reasonable efforts, the Company is unable to obtain the authority that counsel for the Company deems necessary for the grant of Purchase Rights or the lawful issuance and sale of Common Stock under the Plan, and at a
commercially reasonable cost, the Company will be relieved from any liability for failure to grant Purchase Rights and/or to issue and sell Common Stock upon exercise of such Purchase Rights. 

 

	10.	DESIGNATION OF BENEFICIARY. 


(a)    The Company may, but is not obligated to, permit a Participant to submit a form designating a beneficiary who
will receive any shares of Common Stock and/or Contributions from the Participant’s account under the Plan if the Participant dies before such shares and/or Contributions are delivered to the Participant. The Company may, but is not obligated
to, permit the Participant to change such designation of beneficiary. Any such designation and/or change must be on a form approved by the Company or as approved by the Company for use by a Company Designee. 

(b)    If a Participant dies, in the absence of a valid beneficiary designation, the Company will deliver any
shares of Common Stock and/or Contributions to the executor or administrator of the estate of the Participant. If no executor or administrator has been appointed (to the knowledge of the Company), 

  
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the Company, in its sole discretion, may deliver such shares of Common Stock and/or Contributions, without interest, unless the payment of interest is required by applicable laws, to the
Participant’s spouse, dependents or relatives, or if no spouse, dependent or relative is known to the Company, then to such other person as the Company may designate. 
  

	11.	ADJUSTMENTS UPON CHANGES IN COMMON STOCK; CORPORATE TRANSACTIONS. 


(a)    In the event of a Capitalization Adjustment, the Board will appropriately and proportionately adjust:
(i) the class(es) and maximum number of securities subject to the Plan pursuant to Section 3(a), (ii) the class(es) and maximum number of securities by which the share reserve is to increase automatically each year pursuant to
Section 3(a), (iii) the class(es) and number of securities subject to, and the purchase price applicable to outstanding Offerings and Purchase Rights, and (iv) the class(es) and number of securities that are the subject of the purchase
limits under each ongoing Offering. The Board will make these adjustments, and its determination will be final, binding and conclusive. 

(b)    In the event of a Corporate Transaction, then: (i) any surviving corporation or acquiring corporation
(or the surviving or acquiring corporation’s parent company) may assume or continue outstanding Purchase Rights or may substitute similar rights (including a right to acquire the same consideration paid to the stockholders in the Corporate
Transaction) for outstanding Purchase Rights, or (ii) if any surviving or acquiring corporation (or its parent company) does not assume or continue such Purchase Rights or does not substitute similar rights for such Purchase Rights, then
the Participants’ accumulated Contributions will be used to purchase shares of Common Stock (rounded down to the nearest whole share) within ten business days prior to the Corporate Transaction under the outstanding Purchase Rights, and the
Purchase Rights will terminate immediately after such purchase. 
  

	12.	AMENDMENT, TERMINATION OR SUSPENSION OF THE PLAN. 


(a)    The Board may amend the Plan at any time in any respect the Board deems necessary or advisable. However,
except as provided in Section 11(a) relating to Capitalization Adjustments, stockholder approval will be required for any amendment of the Plan for which stockholder approval is required by applicable laws, regulations or listing requirements,
including any amendment that either (i) materially increases the number of shares of Common Stock available for issuance under the Plan, (ii) materially expands the class of individuals eligible to become Participants and receive Purchase
Rights, (iii) materially increases the benefits accruing to Participants under the Plan or materially reduces the price at which shares of Common Stock may be purchased under the Plan, (iv) materially extends the term of the Plan, or
(v) expands the types of awards available for issuance under the Plan, but in each of (i) through (v) above only to the extent stockholder approval is required by applicable laws, regulations, or listing requirements. 

(b)    The Board may suspend or terminate the Plan at any time. No Purchase Rights may be granted under the Plan
while the Plan is suspended or after it is terminated. 
 (c)    Any benefits, privileges, entitlements and
obligations under any outstanding Purchase Rights granted before an amendment, suspension or termination of the Plan will not be materially impaired by any such amendment, suspension or termination except (i) with the consent of the person to
whom such Purchase Rights were granted, (ii) as necessary to comply with any laws, listing requirements, or governmental regulations (including, without limitation, the provisions of Section 423 of the Code and the regulations and other
interpretive guidance issued thereunder relating to Employee Stock Purchase Plans) including without limitation any such regulations or other guidance that may be issued or amended after the Effective Date, or (iii) as necessary to obtain or
maintain any special tax, listing, or regulatory treatment. To be clear, the Board may amend outstanding Purchase Rights without a Participant’s consent if such amendment is necessary to ensure that the Purchase Right and/or the
423 Component complies with the requirements of Section 423 of the Code, or other applicable laws, listing requirements, or governmental regulations. 

  
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 Notwithstanding anything in the Plan to the contrary, the Board will be entitled to:
(i) permit Contributions in excess of the amount designated by a Participant in order to adjust for mistakes in the Company’s processing of properly completed Contribution elections; (ii) establish reasonable waiting and adjustment
periods and/or accounting and crediting procedures to ensure that amounts applied toward the purchase of Common Stock for each Participant properly correspond with amounts withheld from the Participant’s Contributions; (iii) amend any
outstanding Purchase Rights or clarify any ambiguities regarding the terms of any Offering to enable the Purchase Rights to qualify under and/or comply with Section 423 of the Code; and (iv) establish other limitations or procedures as the
Board determines in its sole discretion advisable that are consistent with the Plan. The actions of the Board pursuant to this paragraph will not be considered to alter or impair any Purchase Rights granted under an Offering as they are part of the
initial terms of each Offering and the Purchase Rights granted under each Offering. 
  

	13.	SECTION 409A OF THE CODE; TAX QUALIFICATION. 


(a)    Purchase Rights granted under the 423 Component are intended to be exempt from the application of
Section 409A of the Code under U.S. Treasury Regulation Section 1.409A-1(b)(5)(ii). Purchase Rights granted under the Non-423 Component to U.S. taxpayers
are intended to be exempt from the application of Section 409A of the Code under the short-term deferral exception and any ambiguities will be construed and interpreted in accordance with such intent. Subject to Section 13(b) below,
Purchase Rights granted to U.S. taxpayers under the Non-423 Component will be subject to such terms and conditions that will permit such Purchase Rights to satisfy the requirements of the short-term deferral
exception available under Section 409A of the Code, including the requirement that the shares subject to a Purchase Right be delivered within the short-term deferral period. Subject to Section 13(b) below, in the case of a Participant
who would otherwise be subject to Section 409A of the Code, to the extent the Board determines that a Purchase Right or the exercise, payment, settlement or deferral thereof is subject to Section 409A of the Code, the Purchase Right will
be granted, exercised, paid, settled or deferred in a manner that will comply with Section 409A of the Code, including U.S. Department of Treasury regulations and other interpretive guidance issued thereunder, including, without limitation, any
such regulations or other guidance that may be issued after the adoption of the Plan. Notwithstanding the foregoing, the Company will have no liability to a Participant or any other party if the Purchase Right that is intended to be exempt from
or compliant with Section 409A of the Code is not so exempt or compliant or for any action taken by the Board with respect thereto. 

(b)    Although the Company may endeavor to (i) qualify a Purchase Right for special tax treatment under the
laws of the United States or jurisdictions outside of the United States or (ii) avoid adverse tax treatment (e.g., under Section 409A of the Code), the Company makes no representation to that effect and expressly disavows any
covenant to maintain special or to avoid unfavorable tax treatment, notwithstanding anything to the contrary in this Plan, including Section 13(a) above. The Company will be unconstrained in its corporate activities without regard to the
potential negative tax impact on Participants under the Plan. 
  

	14.	TAX WITHHOLDING 

 The Participant will make adequate
provision to satisfy the Tax-Related Items withholding obligations, if any, of the Company and/or the applicable Designated Company which arise with respect to Participant’s participation in the Plan or
upon the disposition of the shares of the Common Stock. The Company and/or the Designated Company may, but will not be obligated to, withhold from the 

  
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Participant’s compensation or any other payments due the Participant the amount necessary to meet such withholding obligations or withhold from the proceeds of the sale of shares of Common
Stock or any other method of withholding that the Company and/or the Designated Company deems appropriate. The Company and/or the Designated Company will have the right to take such other action as may be necessary in the opinion of the Company or a
Designated Company to satisfy withholding and/or reporting obligations for such Tax-Related Items. 
  

	15.	EFFECTIVE DATE OF PLAN. 

 The
Plan will become effective immediately prior to and contingent upon the IPO Date. No Purchase Rights will be exercised unless and until the Plan has been approved by the stockholders of the Company, which approval must be within 12 months before or
after the date the Plan is adopted (or if required under Section 12(a) above, materially amended) by the Board. 
  

	16.	MISCELLANEOUS PROVISIONS. 


(a)    Proceeds from the sale of shares of Common Stock pursuant to Purchase Rights will constitute general funds of
the Company. 
 (b)    A Participant will not be deemed to be the holder of, or to have any of the rights of a
holder with respect to, shares of Common Stock subject to Purchase Rights unless and until the Participant’s shares of Common Stock acquired upon exercise of Purchase Rights are recorded in the books of the Company (or its transfer agent). 

(c)    The Plan and Offering do not constitute an employment contract. Nothing in the Plan or in the Offering will
in any way alter the at-will nature of a Participant’s employment, if applicable, or be deemed to create in any way whatsoever any obligation on the part of any Participant to continue in the employ of
the Company, a Related Corporation, or an Affiliate, or on the part of the Company, a Related Corporation or an Affiliate to continue the employment of a Participant. 

(d)    The provisions of the Plan will be governed by the laws of the State of Delaware without resort to that
state’s conflicts of laws rules. 
 (e)    If any particular provision of the Plan is found to be invalid or
otherwise unenforceable, such provision will not affect the other provisions of the Plan, but the Plan will be construed in all respects as if such invalid provision were omitted. 

(f)    If any provision of the Plan does not comply with applicable law or regulations, such provision shall be
construed in such a manner as to comply with applicable law or regulations. 
  

	17.	DEFINITIONS. 

 As used in the Plan, the following definitions will apply
to the capitalized terms indicated below: 
 (a)    “423 Component” means the part of the
Plan, which excludes the Non-423 Component, pursuant to which Purchase Rights that satisfy the requirements for an Employee Stock Purchase Plan may be granted to Eligible Employees. 

(b)    “Affiliate” means any entity, other than a Related Corporation, in which the Company
has an equity or other ownership interest or that is directly or indirectly controlled by, controls, or is under common control with the Company, in all cases, as determined by the Board, whether now or hereafter existing. 

  
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 (c)    “Board” means the board of
directors of the Company. 
 (d)    “Capital Stock” means each and every class of
common stock of the Company, regardless of the number of votes per share. 
 (e)    “Capitalization
Adjustment” means any change that is made in, or other events that occur with respect to, the Common Stock subject to the Plan or subject to any Purchase Right after the Effective Date without the receipt of consideration by the Company
through merger, consolidation, reorganization, recapitalization, reincorporation, stock dividend, dividend in property other than cash, large nonrecurring cash dividend, stock split, liquidating dividend, combination of shares, exchange of shares,
change in corporate structure or other similar equity restructuring transaction, as that term is used in Financial Accounting Standards Board Accounting Standards Codification Topic 718 (or any successor thereto). Notwithstanding the foregoing, the
conversion of any convertible securities of the Company will not be treated as a Capitalization Adjustment. 

(f)    “Code” means the U.S. Internal Revenue Code of 1986, as amended, including
any applicable regulations and guidance thereunder. 
 (g)    “Committee”
means a committee of one or more members of the Board to whom authority has been delegated by the Board in accordance with Section 2(c). 

(h)    “Common Stock” means, as of the IPO Date, the common stock of the Company having one
vote per share. 
 (i)    “Company” means Tenable Holdings, Inc., a Delaware corporation,
and any successor corporation thereto. 
 (j)    “Contributions” means the payroll
deductions and/or other payments specifically provided for in the Offering that a Participant contributes to fund the exercise of a Purchase Right. A Participant may make additional payments into his or her account if specifically provided for in
the Offering, and then only if the Participant has not already contributed the maximum permitted amount of payroll deductions and/or other payments during the Offering. 

(k)    “Corporate Transaction” means the consummation, in a single transaction or in a
series of related transactions, of any one or more of the following events: 
 (i)    a sale or other
disposition of all or substantially all, as determined by the Board in its sole discretion, of the consolidated assets of the Company and its Subsidiaries; 

(ii)    a sale or other disposition of more than 50% of the outstanding securities of the Company; 

(iii)    a merger, consolidation or similar transaction following which the Company is not the surviving
corporation; or 
 (iv)    a merger, consolidation or similar transaction following which the Company is the
surviving corporation but the shares of Common Stock outstanding immediately preceding the merger, consolidation or similar transaction are converted or exchanged by virtue of the merger, consolidation or similar transaction into other property,
whether in the form of securities, cash or otherwise. 

  
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 (l)    “Designated 423 Corporation” means any
Related Corporation selected by the Board as participating in the 423 Component. 
 (m)    “Designated
Company” means any Designated Non-423 Corporation or Designated 423 Corporation, provided, however, that at any given time, a Related Corporation participating in the 423 Component shall not be a
Related Corporation participating in the Non-423 Component. 

(n)    “Designated Non-423 Corporation” means any
Related Corporation or Affiliate selected by the Board as participating in the Non-423 Component. 

(o)    “Director” means a member of the Board. 

(p)    “Effective Date” means the effective date of the Plan, as set forth in
Section 13. 
 (q)    “Eligible Employee” means an Employee who meets the
requirements set forth in the document(s) governing the Offering for eligibility to participate in the Offering, provided that such Employee also meets the requirements for eligibility to participate set forth in the Plan. 

(r)    “Employee” means any person, including an Officer or Director, who is
“employed” for purposes of Section 423(b)(4) of the Code by the Company or a Related Corporation (including an Affiliate). However, service solely as a Director, or payment of a fee for such services, will not cause a Director to be
considered an “Employee” for purposes of the Plan. 
 (s)    “Employee Stock Purchase
Plan” means a plan that grants Purchase Rights intended to be options issued under an “employee stock purchase plan,” as that term is defined in Section 423(b) of the Code. 

(t)    “Exchange Act” means the U.S. Securities Exchange Act of 1934, as amended and
the rules and regulations promulgated thereunder. 
 (u)    “Fair Market Value” means, as
of any date, the value of the Common Stock determined as follows: 
 (i)    If the Common Stock is listed on any
established stock exchange or traded on any established market, the Fair Market Value of a share of Common Stock will be, unless otherwise determined by the Board, the closing sales price for such stock as quoted on such exchange or
market (or the exchange or market with the greatest volume of trading in the Common Stock) on the date of determination, as reported in such source as the Board deems reliable. Unless otherwise provided by the Board, if there is no
closing sales price for the Common Stock on the date of determination, then the Fair Market Value will be the closing sales price on the last preceding date for which such quotation exists. 

(ii)    In the absence of such markets for the Common Stock, the Fair Market Value will be determined by the Board
in good faith in compliance with applicable laws and regulations and in a manner that complies with Sections 409A of the Code. 

(iii)    Notwithstanding the foregoing, for any Offering that commences on the IPO Date, the Fair Market Value of
the shares of Common Stock on the Offering Date will be the price per share at which shares are first sold to the public in the Company’s initial public offering as specified in the final prospectus for that initial public offering. 

  
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 (v)    “IPO Date” means the date of the
underwriting agreement between the Company and the underwriter(s) managing the initial public offering of the Common Stock, pursuant to which the Common Stock is priced for the initial public offering. 

(w)    “Non-423 Component” means the part of the
Plan, which excludes the 423 Component, pursuant to which Purchase Rights that are not intended to satisfy the requirements for an Employee Stock Purchase Plan may be granted to Eligible Employees. 

(x)    “Offering” means the grant to Eligible Employees of Purchase Rights, with the
exercise of those Purchase Rights automatically occurring at the end of one or more Purchase Periods. The terms and conditions of an Offering will generally be set forth in the “Offering Document” approved by the Board for
that Offering. 
 (y)    “Offering Date” means a date selected by the Board for an
Offering to commence. 
 (z)    “Officer” means a person who is an officer
of the Company or a Related Corporation or Affiliate within the meaning of Section 16 of the Exchange Act. 

(aa)    “Participant” means an Eligible Employee who holds an outstanding Purchase
Right. 
 (bb)    “Plan” means this Tenable Holdings, Inc. 2018 Employee Stock
Purchase Plan, including both the 423 Component and the Non-423 Component, as amended from time to time. 

(cc)    “Purchase Date” means one or more dates during an Offering selected by the
Board on which Purchase Rights will be exercised and on which purchases of shares of Common Stock will be carried out in accordance with such Offering. 

(dd)    “Purchase Period” means a period of time specified within an Offering, generally
beginning on the Offering Date or on the first Trading Day following a Purchase Date, and ending on a Purchase Date. An Offering may consist of one or more Purchase Periods. 

(ee)    “Purchase Right” means an option to purchase shares of Common Stock granted
pursuant to the Plan. 
 (ff)    “Related Corporation” means any “parent
corporation” or “subsidiary corporation” of the Company whether now or subsequently established, as those terms are defined in Sections 424(e) and (f), respectively, of the Code. 

(gg)    “Securities Act” means the U.S. Securities Act of 1933, as amended. 

(hh)    “Tax-Related Items” means any income tax,
social insurance, payroll tax, fringe benefit tax, payment on account or other tax-related items arising in relation to a Participant’s participation in the Plan. 

(ii)    “Trading Day” means any day on which the exchange(s) or market(s) on which
shares of Common Stock are listed, including but not limited to the NYSE, Nasdaq Global Select Market, the Nasdaq Global Market, the Nasdaq Capital Market or any successors thereto, is open for trading. 

  
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