CVE-2026-86247: Apache Tomcat Native: Client certificate requirements can be down-graded

[Mark Thomas <markt () apache org>]

Severity: moderate

Affected versions:

- Apache Tomcat Native 2.0.0 through 2.0.15
- Apache Tomcat Native 1.3.0 through 1.3.8

Description:

Race condition within a thread vulnerability in Apache Tomcat Native 
allowed client certificate verification requirements to be down-graded 
for some configurations.



This issue affects Apache Tomcat Native: from 2.0.0 through 2.0.15, from 
1.3.0 through 1.3.8. Unsupported versions may also be affected.



Users are recommended to upgrade to version 2.0.16 or 1.3.9, which fixes 
the issue.

References:

https://lists.apache.org/thread/obsson6zhvfg0wsp2bx602l61ltj87r1
https://tomcat.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-86247