CVE-2026-43513: Apache Tomcat: LockOutRealm treats user names as case-sensitive

[Mark Thomas <markt () apache org>]

Severity: low

Affected versions:

- Apache Tomcat 11.0.0-M1 through 11.0.21
- Apache Tomcat 10.1.0-M1 through 10.1.54
- Apache Tomcat 9.0.0.M1 through 9.0.117
- Apache Tomcat 8.5.0 through 8.5.100
- Apache Tomcat 7.0.0 through 7.0.109
- Apache Tomcat before 7.00 unknown

Description:

Improper Handling of Case Sensitivity vulnerability in LockOutRealm in 
Apache Tomcat.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.21, from 
10.1.0-M1 through 10.1.54, from 9.0.0.M1 through 9.0.117, from 8.5.0 
through 8.5.100, from 7.0.0 through 7.0.109.
Older unsupported versions may also be affected.

Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 
which fix the issue.

References:

https://lists.apache.org/thread/ytjcgldshj73lcnd1sh95od5hrghwogp
https://tomcat.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-43513