CVE-2026-77791

Apache Tomcat: DoS via busy wait during WebSocket close

Published Sep 23, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Redhat
Redhat hummingbird
Weaknesses CWE-1050
CPEs cpe:/a:redhat:hummingbird:1
Vendors & Products Redhat
Redhat hummingbird
References
Metrics threat_severity

None

threat_severity

Important

Type Values Removed Values Added
First Time appeared Apache
Apache apache Tomcat
Vendors & Products Apache
Apache apache Tomcat
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Apache Tomcat: DoS via busy wait during WebSocket close
Weaknesses CWE-400
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
apache
Published
Updated
Sep 23, 2026, 6:10 PM
Reserved
Aug 21, 2026, 12:38 PM
Status
Awaiting Analysis
Published
Sep 23, 2026, 12:17 PM
Modified
Sep 23, 2026, 7:19 PM
Severity
Important
Public date
Sep 23, 2026, 11:20 AM