CVE-2026-77791
Received Received - Intake

Uncontrolled Resource Consumption in Apache Tomcat WebSocket Close Message

Publication date: 2026-09-23

Last updated on: 2026-09-23

Assigner: Apache Software Foundation

Description
Uncontrolled Resource Consumption vulnerability in Apache Tomcat during sending of WebSocket close message enabled a DoS attack. This issue affects Apache Tomcat: from 11.0.0-M5 through 11.0.25, from 10.1.8 through 10.1.59, from 9.0.74 through 9.0.121. The following versions were EOL at the time the CVE was created but are known to be affected: from 8.5.88 through 8.5.100. Other unsupported versions may also be affected. Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.0.122, which fix the issue.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-09-23
Last Modified
2026-09-23
Generated
2026-09-23
AI Q&A
2026-09-23
EPSS Evaluated
N/A
NVD
CVE-2026-77791
EUVD
EUVD-2026-85229

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
apache tomcat From 11.0.0-M5 (inc) to 11.0.25 (inc)
apache tomcat From 10.1.8 (inc) to 10.1.59 (inc)
apache tomcat From 9.0.74 (inc) to 9.0.121 (inc)
apache tomcat From 8.5.88 (inc) to 8.5.100 (inc)

Helpful Resources

Exploitability

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

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This vulnerability in Apache Tomcat involves uncontrolled resource consumption when sending a WebSocket close message. It allows a denial-of-service (DoS) attack by consuming excessive server resources during the process.

Detection Guidance

Detecting this vulnerability requires checking the Apache Tomcat version in use. If your system runs Tomcat versions 11.0.0-M5 to 11.0.25, 10.1.8 to 10.1.59, 9.0.74 to 9.0.121, or 8.5.88 to 8.5.100, it is vulnerable. Use commands like 'catalina.sh version' or check the version in the Tomcat manager interface.

Impact Analysis

This vulnerability can lead to degraded performance or complete unavailability of the Apache Tomcat server. It may cause slow response times, crashes, or service interruptions for applications relying on WebSocket connections.

Compliance Impact

This vulnerability could lead to denial-of-service (DoS) conditions, potentially disrupting services handling sensitive data. For GDPR, this may impact availability of personal data processing systems, while for HIPAA, it could affect the integrity and availability of protected health information systems.

Mitigation Strategies

Upgrade Apache Tomcat to version 11.0.26, 10.1.60, or 9.0.122 or later to fix the vulnerability.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-77791. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart