CVE-2026-66299

Analyzed Analyzed - Analysis Complete

Uncontrolled Resource Consumption in Apache Tomcat WebSocket Example

Publication date: 2026-07-28

Last updated on: 2026-08-05

Assigner: Apache Software Foundation

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.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-07-28

Last Modified

2026-08-05

Generated

2026-08-17

AI Q&A

2026-07-28

EPSS Evaluated

2026-08-16

NVD

CVE-2026-66299

EUVD

EUVD-2026-49855

Affected Vendors & Products

Vendor	Product	Version / Range
apache	tomcat	11.0.0
apache	tomcat	11.0.0
apache	tomcat	11.0.0
apache	tomcat	11.0.0
apache	tomcat	11.0.0
apache	tomcat	11.0.0
apache	tomcat	11.0.0
apache	tomcat	From 10.1.24 (inc) to 10.1.58 (exc)
apache	tomcat	From 9.0.89 (inc) to 9.0.121 (exc)
apache	tomcat	From 11.0.1 (inc) to 11.0.25 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-400	The product does not properly control the allocation and maintenance of a limited resource.

Attack-Flow Graph

Executive Summary

This is an Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example. It allows an attacker to consume excessive server resources by exploiting the chat example, potentially leading to denial of service.

Detection Guidance

Check if the Tomcat examples web application is deployed by verifying the presence of the /examples/ path in your Tomcat webapps directory. If deployed, inspect logs for unusual WebSocket connection attempts or resource spikes.

Impact Analysis

If you are running an affected version of Apache Tomcat with the examples web application deployed, an attacker could exploit this to consume server resources, causing performance degradation or a crash. Removing the examples web application mitigates the risk.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or other standards as it is an uncontrolled resource consumption issue in a non-default example application. Standards typically focus on data protection, access control, and system integrity rather than resource exhaustion in demo code.

Mitigation Strategies

Remove the examples web application from your Tomcat installation. Alternatively, upgrade Tomcat to version 11.0.25, 10.1.58, or 9.0.121 (when available) to patch the vulnerability.

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