The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.

What CVEs are caused by CWE-307?

389 recorded CVEs are attributed to CWE-307, including CVE-2026-6853, CVE-2026-8760, CVE-2020-37228.

How do you prevent CWE-307?

Common protection mechanisms include:

How is CWE-307 detected?

Dynamic Analysis with Automated Results Interpretation: According to SOAR [REF-1479], the following detection techniques may be useful:

What are the consequences of CWE-307?

Exploiting CWE-307 can lead to: Bypass Protection Mechanism.

Is CWE-307 actively exploited?

389 recorded CVEs are caused by CWE-307; none are currently in CISA's KEV catalog of actively exploited flaws.

CWE-307: Improper Restriction of Excessive Authentication Attempts

Code examples

Illustrative examples from MITRE showing how the weakness appears in code.

In January 2009, an attacker was able to gain administrator access to a Twitter server because the server did not restrict the number of login attempts [REF-236]. The attacker targeted a member of Twitter's support team and was able to successfully guess the member's password using a brute force attack by guessing a large number of common words. After gaining access as the member of the support staff, the attacker used the administrator panel to gain access to 33 accounts that belonged to celebrities and politicians. Ultimately, fake Twitter messages were sent that appeared to come from the compromised accounts.

The following code, extracted from a servlet's doPost() method, performs an authentication lookup every time the servlet is invoked.

Vulnerable example

java

String username = request.getParameter("username");

However, the software makes no attempt to restrict excessive authentication attempts.

This code attempts to limit the number of login attempts by causing the process to sleep before completing the authentication.

Vulnerable example

php

$username = $_POST['username'];

However, there is no limit on parallel connections, so this does not increase the amount of time an attacker needs to complete an attack.

In the following C/C++ example the validateUser method opens a socket connection, reads a username and password from the socket and attempts to authenticate the username and password.

Vulnerable example

int validateUser(char *host, int port)

Safe example

int validateUser(char *host, int port)

The validateUser method will continuously check for a valid username and password without any restriction on the number of authentication attempts made. The method should limit the number of authentication attempts made to prevent brute force attacks as in the following example code.

Consider this example from a real-world attack against the iPhone [REF-1218]. An attacker can use brute force methods; each time there is a failed guess, the attacker quickly cuts the power before the failed entry is recorded, effectively bypassing the intended limit on the number of failed authentication attempts. Note that this attack requires removal of the cell phone battery and connecting directly to the phone's power source, and the brute force attack is still time-consuming.

CWE-307: Improper Restriction of Excessive Authentication Attempts

Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

How to prevent it

How to detect it

Dynamic Analysis with Automated Results Interpretation

Dynamic Analysis with Manual Results Interpretation

Manual Static Analysis - Source Code

Automated Static Analysis - Source Code

Automated Static Analysis

Architecture or Design Review

Code examples

Illustrative examples

Terminology & mappings

Mapped taxonomies

Attack patterns

Frequently asked questions

What is CWE-307?

What CVEs are caused by CWE-307?

How do you prevent CWE-307?

How is CWE-307 detected?

What are the consequences of CWE-307?

Is CWE-307 actively exploited?

References

Stay ahead of CWE-307

Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

How to prevent it

How to detect it

Dynamic Analysis with Automated Results Interpretation

Dynamic Analysis with Manual Results Interpretation

Manual Static Analysis - Source Code

Automated Static Analysis - Source Code

Automated Static Analysis

Architecture or Design Review

Code examples

Illustrative examples

Related weaknesses

Parent

Terminology & mappings

Mapped taxonomies

Attack patterns

Frequently asked questions

What is CWE-307?

What CVEs are caused by CWE-307?

How do you prevent CWE-307?

How is CWE-307 detected?

What are the consequences of CWE-307?

Is CWE-307 actively exploited?

References

Stay ahead of CWE-307