Resource exhaustion in Apache Tomcat - CVE-2026-77791
Published: September 23, 2026
Vulnerability identifier: #VU151844
CSH Severity: Medium
CVSS v4: 8.7 [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]
CVE-ID: CVE-2026-77791
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a busy wait in WebSocket close message handling when sending a WebSocket close message. A remote attacker can trigger the busy wait to cause a denial of service.
Affected software
Apache Tomcat
How to mitigate CVE-2026-77791
Install security update from vendor's website.
Apache Tomcat - addressed in versions 9.0.122, 10.1.60, 11.0.26