CVE-2026-77791 Security Details

CVE ID

CVE-2026-77791

CWE

CWE-400

CVE 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.

Published

Sep 25, 2026

CVSS Score & Severity

8.7High

CVSS Vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

EPSS Score

0.679%

Malware

malware

KEV Status

Not in KEV Catalog: No known exploits

Vulnerable Methods

org/apache/tomcat/websocket/server/WsRemoteEndpointImplServer.acquireMessagePartInProgressSemaphore(BJ)Z

JVM

Affected Ecosystems

affected

Source

National Vulnerability Database

References

Apache · AnnouncementPROJECT

Apache · Security advisoryPROJECT