Input validation error in Apache Tomcat - CVE-2026-87022
Published: September 23, 2026
Vulnerability identifier: #VU151838
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-87022
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to smuggle WebSocket messages.
The vulnerability exists due to improper handling of a length parameter in WebSocket per-message-deflate processing when processing WebSocket messages with per-message-deflate enabled. A remote attacker can send a crafted WebSocket message to smuggle WebSocket messages.
Only WebSocket connections using per-message-deflate are affected.
Affected software
Apache Tomcat
How to mitigate CVE-2026-87022
Install security update from vendor's website.
Apache Tomcat - addressed in versions 9.0.122, 10.1.60, 11.0.26