All vulnerabilities
CVE-2026-76183

Apache Tomcat: Bypass of security constraints for WebSocket endpoints

Apache Software Foundation Apache TomcatWeb servers
Open in ThreatlineRecord JSON
CVSS
9.8Critical
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.39%Chance of exploitation activity in the next 30 days, higher than 31% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Published23 Sep 2026Updated 30 Sep 2026CVE List

What fixes it

No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.

Timeline

  1. 23 Sep 2026, 11:16 UTCPublishedCVE List
  2. 23 Oct 2026, 16:30 UTCExploit code publicGitHub proof-of-concept repositories

Reports 2

2 outlets mention it. Reports are not confirmation; each links to its source.

Description

Authentication Bypass by Alternate Name vulnerability in Apache Tomcat allowed the security constraints for any WebSocket endpoint to be bypassed.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.0.M1 through 9.0.121.

The following versions were EOS at the time the CVE was created but are known to be affected: from 8.5.0 through 8.5.100, from 7.0.43 through 7.0.109. 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.

Text from CVE List

Affected versions 6

  • Apache Tomcataffected: 11.0.0-M1 through 11.0.25CVE List
  • Apache Tomcataffected: 10.1.0-M1 through 10.1.59CVE List
  • Apache Tomcataffected: 9.0.0.M1 through 9.0.121CVE List
  • Apache Tomcataffected: 8.5.0 through 8.5.100CVE List
  • Apache Tomcataffected: 7.0.43 through 7.0.109CVE List
  • Apache Tomcatunaffected: all versions before 7.0.43CVE List

References 1