CVE-2026-87022 Apache Tomcat - WebSocket message smuggling with
per-message-deflate
Severity: Low
Vendor: The Apache Software Foundation
Versions Affected:
Apache Tomcat 11.0.0-M1 to 11.0.25
Apache Tomcat 10.1.0-M1 to 10.1.59
Apache Tomcat 9.0.0.M1 to 9.0.121
Description:
Improper handling of length parameter allows WebSocket message smuggling
when per-message-deflate is used.
Mitigation:
Users of the affected versions should apply one of the following
mitigations:
- Remove the examples web application
- Upgrade to Apache Tomcat 11.0.26
- Upgrade to Apache Tomcat 10.1.60
- Upgrade to Apache Tomcat 9.0.122
Credit:
This issue was identified by:
- krsecurity(kongr)
History:
2026-09-23 Original advisory
References:
[1] https://tomcat.apache.org/security-11.html
[2] https://tomcat.apache.org/security-10.html
[3] https://tomcat.apache.org/security-9.html
