CVE-2026-66299
Apache Tomcat: DoS via WebSocket chat example
Description
Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example. This issue affects Apache Tomcat: from 11.0.0-M20 through 11.0.24, from 10.1.24 through 10.1.57, from 9.0.89 through 9.0.120. Users who have followed the security guidance to remove the examples web application are not affected by this issue. Users are recommended to remove the examples web application or to upgrade to version 11.0.25, 10.1.58 or 9.0.121 (when released), which fix the issue.
INFO
Published Date :
July 28, 2026, 3:17 p.m.
Last Modified :
July 28, 2026, 4:20 p.m.
Remotely Exploit :
No
Source :
[email protected]
Solution
- Remove the examples web application.
- Upgrade to Apache Tomcat 11.0.25.
- Upgrade to Apache Tomcat 10.1.58.
- Upgrade to Apache Tomcat 9.0.121 (when released).
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-66299.
| URL | Resource |
|---|---|
| https://lists.apache.org/thread/8owczcc1o8qw1rxmg9gvfk4w2jnh4l5k |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-66299 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-66299
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-66299 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-66299 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Jul. 28, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Apache Software Foundation', 'product': 'Apache Tomcat', 'versions': [{'status': 'affected', 'version': '11.0.0-M20', 'versionType': 'semver', 'lessThanOrEqual': '11.0.24'}, {'status': 'affected', 'version': '10.1.24', 'versionType': 'semver', 'lessThanOrEqual': '10.1.57'}, {'status': 'affected', 'version': '9.0.89', 'versionType': 'semver', 'lessThanOrEqual': '9.0.120'}, {'status': 'unaffected', 'version': '0', 'versionType': 'semver', 'lessThanOrEqual': '8.5.100'}], 'defaultStatus': 'unaffected'}] Added Description Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example. This issue affects Apache Tomcat: from 11.0.0-M20 through 11.0.24, from 10.1.24 through 10.1.57, from 9.0.89 through 9.0.120. Users who have followed the security guidance to remove the examples web application are not affected by this issue. Users are recommended to remove the examples web application or to upgrade to version 11.0.25, 10.1.58 or 9.0.121 (when released), which fix the issue. Added CWE CWE-400 Added Reference https://lists.apache.org/thread/8owczcc1o8qw1rxmg9gvfk4w2jnh4l5k