<PAGE>   1
                                                                    EXHIBIT 4.26

                      SECOND AMENDMENT TO SECURITIES PURCHASE AGREEMENT

        THIS SECOND AMENDMENT TO SECURITIES PURCHASE AGREEMENT is dated as of
July 26, 2000, by and among CyberCash, Inc., a Delaware corporation, with
headquarters located at 2100 Reston Parkway, 3rd Floor, Reston, Virginia 20191
(the "COMPANY") and each of the purchasers set forth on the signature pages
hereto (the "BUYERS").

        WHEREAS, the Company and the Buyers desire to amend Section 1(a)(ii) of
that certain Securities Purchase Agreement dated as of August 19, 1999 by and
among the Company and the Buyers, as amended by that certain Amendment to
Securities Purchase Agreement dated as of September 7, 1999 by and among the
Company and the Buyers (as amended, the "AGREEMENT").

        NOW, THEREFORE, the Company and each of the Buyers severally (and not
jointly) hereby agree as follows:

        1.     AMENDMENT TO AGREEMENT.  Section 1(a)(ii) of the Agreement is
hereby amended and restated in its entirety to read as follows:

               "In the event that the average of the closing bid prices of the
               Common Stock as reported on Nasdaq for the ten (10) consecutive
               trading days immediately preceding October 19, 2000 (the "RESET
               Price") is less than the Closing Price, the Company shall, within
               three (3) business days of October 19, 2000, be required to
               either: (i) deliver to each Buyer additional shares of Common
               Stock (the "ADDITIONAL SHARES") in an amount such that the total
               number of shares of Common Stock issued to such Buyer (i.e., the
               Common Shares issued on the Closing Date plus the Additional
               Shares) equals (x) the Purchase Price paid by such Buyer on the
               Closing Date, divided by (y) the Reset Price; or (ii) pay to each
               Buyer in cash an amount equal to (x) the number of Additional
               Shares issuable to such Buyer pursuant to the preceding clause
               (i), multiplied by (y) the Reset Price; provided, however, that
               the Company may only elect to issue the Additional Shares in lieu
               of paying cash to any such Buyer if (and to the extent that) such
               issuance (i) is then registered pursuant to the Registration
               Statement and such Registration Statement is effective and (ii)
               would not require the approval of the Company's shareholders
               under Rule 4460(i) of the Nasdaq Marketplace Rules. In the event
               that the Company is unable to issue the Additional Shares due to
               the failure of either of the conditions set forth in the
               preceding proviso, the Company will pay to each of the Buyers the
               cash amount specified in the preceding sentence."


<PAGE>   2





        2.     EFFECT OF AMENDMENT.  This Amendment shall not effect any of the
other terms and conditions of the Agreement, which terms and conditions shall
remain in full force and effect.


        IN WITNESS WHEREOF, the undersigned Buyers and the Company have caused
this Agreement to be duly executed as of the date first above written.

CYBERCASH, INC.

By: /s/ John H. Karnes
    ------------------
    John H. Karnes
    Executive Vice President and Chief Financial Officer

RGC INTERNATIONAL INVESTORS, LDC
By:     Rose Glen Capital Management, L.P., Investment Manager
        By:    RGC General Partner Corp., as General Partner

By: /s/ Gary S. Kaminsky
    --------------------
    Gary S. Kaminsky
    Managing Director






                                       2