The product does not properly limit the number or frequency of interactions that it has with an actor, such as the number of incoming requests.
This can allow the actor to perform actions more frequently than expected. The actor could be a human or an automated process such as a virus or bot. This could be used to cause a denial of service, compromise program logic (such as limiting humans to a single vote), or other consequences. For example, an authentication routine might not limit the number of times an attacker can guess a password. Or, a web site might conduct a poll but only expect humans to vote a maximum of once a day.

Primary

Insufficient anti-automation
The term "insufficient anti-automation" focuses primarly on non-human actors such as viruses or bots, but the scope of this CWE entry is broader.

Brute force
Vulnerabilities that can be targeted using brute force attacks are often symptomatic of this weakness.

Architecture and Design

Implementation

Operation

Availability
Access Control
Other
DoS: Resource Consumption (Other)
Bypass Protection Mechanism
Other

In the following code a username and password is read from a socket and an attempt is made to authenticate the username and password. The code will continuously checked the socket for a username and password until it has been authenticated.

char username[USERNAME_SIZE];char password[PASSWORD_SIZE];
while (isValidUser == 0) {
if (getNextMessage(socket, username, USERNAME_SIZE) > 0) {if (getNextMessage(socket, password, PASSWORD_SIZE) > 0) {isValidUser = AuthenticateUser(username, password);}}
}return(SUCCESS);

This code does not place any restriction on the number of authentication attempts made. There should be a limit on the number of authentication attempts made to prevent brute force attacks as in the following example code.

int count = 0;while ((isValidUser == 0) && (count < MAX_ATTEMPTS)) {
if (getNextMessage(socket, username, USERNAME_SIZE) > 0) {if (getNextMessage(socket, password, PASSWORD_SIZE) > 0) {isValidUser = AuthenticateUser(username, password);}}count++;
}if (isValidUser) {return(SUCCESS);}else {return(FAIL);}

CVE-2024-50653
Chain: e-commerce product has a "front-end restriction" for coupon use (CWE-602), but the server does not restrict the number of requests for the same coupon (CWE-799)
https://www.cve.org/CVERecord?id=CVE-2024-50653

CVE-2002-1876
Mail server allows attackers to prevent other users from accessing mail by sending large number of rapid requests.
https://www.cve.org/CVERecord?id=CVE-2002-1876

21
Insufficient Anti-Automation

Allowed-with-Review
This CWE entry is a Class and might have Base-level children that would be more appropriate
Examine children of this entry to see if there is a better fit

CWE Content Team
MITRE
2010-01-15
1.8
2010-02-16
New entry to handle anti-automation as identified in WASC.

CWE Content Team
MITRE
2010-04-05
updated Demonstrative_Examples

CWE Content Team
MITRE
2011-03-29
updated Observed_Examples, Relationships

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences

CWE Content Team
MITRE
2017-11-08
updated Demonstrative_Examples

CWE Content Team
MITRE
2020-02-24
updated Relationships

CWE Content Team
MITRE
2021-10-28
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
2025-12-11
4.19
2025-12-11
updated Applicable_Platforms, Observed_Examples, Relationships