The product's resource pool is not large enough to handle peak demand, which allows an attacker to prevent others from accessing the resource by using a (relatively) large number of requests for resources.
Frequently the consequence is a "flood" of connection or sessions.

Primary

Architecture and Design

Implementation

Operation

Availability
Integrity
Other
DoS: Crash, Exit, or Restart
Other
Floods often cause a crash or other problem besides denial of the resource itself; these are likely examples of *other* vulnerabilities, not an insufficient resource pool.

Architecture and Design
Do not perform resource-intensive transactions for unauthenticated users and/or invalid requests.

Architecture and Design
Consider implementing a velocity check mechanism which would detect abusive behavior.

Operation
Consider load balancing as an option to handle heavy loads.

Implementation
Make sure that resource handles are properly closed when no longer needed.

Architecture and Design
Identify the system's resource intensive operations and consider protecting them from abuse (e.g. malicious automated script which runs the resources out).

In the following snippet from a Tomcat configuration file, a JDBC connection pool is defined with a maximum of 5 simultaneous connections (with a 60 second timeout). In this case, it may be trivial for an attacker to instigate a denial of service (DoS) by using up all of the available connections in the pool.

<Resource name="jdbc/exampledb"auth="Container"type="javax.sql.DataSource"removeAbandoned="true"removeAbandonedTimeout="30"maxActive="5"maxIdle="5"maxWait="60000"username="testuser"password="testpass"driverClassName="com.mysql.jdbc.Driver"url="jdbc:mysql://localhost/exampledb"/>

CVE-1999-1363
Large number of locks on file exhausts the pool and causes crash.
https://www.cve.org/CVERecord?id=CVE-1999-1363

CVE-2001-1340
Product supports only one connection and does not disconnect a user who does not provide credentials.
https://www.cve.org/CVERecord?id=CVE-2001-1340

CVE-2002-0406
Large number of connections without providing credentials allows connection exhaustion.
https://www.cve.org/CVERecord?id=CVE-2002-0406

Insufficient Resource Pool

A9
Denial of Service
CWE More Specific

TPS00-J
Use thread pools to enable graceful degradation of service during traffic bursts

Allowed
This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

PLOVER
2006-07-19
Draft 3
2006-07-19

Sean Eidemiller
Cigital
2008-07-01
added/updated demonstrative examples

Eric Dalci
Cigital
2008-07-01
updated Potential_Mitigations, Time_of_Introduction

CWE Content Team
MITRE
2008-09-08
updated Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings

CWE Content Team
MITRE
2008-10-14
updated Description, Relationships

CWE Content Team
MITRE
2009-07-27
updated Demonstrative_Examples

CWE Content Team
MITRE
2009-10-29
updated Common_Consequences

CWE Content Team
MITRE
2010-02-16
updated References

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences, Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2012-05-11
updated Relationships

CWE Content Team
MITRE
2012-10-30
updated Potential_Mitigations

CWE Content Team
MITRE
2014-06-23
updated Other_Notes, Potential_Mitigations

CWE Content Team
MITRE
2014-07-30
updated Relationships

CWE Content Team
MITRE
2017-11-08
updated Applicable_Platforms, Functional_Areas, References

CWE Content Team
MITRE
2018-03-27
updated References

CWE Content Team
MITRE
2019-01-03
updated Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2020-02-24
updated Relationships

CWE Content Team
MITRE
2023-01-31
updated Description

CWE Content Team
MITRE
2023-04-27
updated Relationships

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2025-04-03
4.17
2025-04-03
updated Type

CWE Content Team
MITRE
2025-12-11
4.19
2025-12-11
updated Weakness_Ordinalities