CVE-2026-43513

Apache Tomcat: LockOutRealm treats user names as case-sensitive

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.

Patch Available

Fix available through Seal Security. No upgrade required, protect your application instantly.

Fix without upgrading

Score

7.5

Severity

High

Ecosystem

Java

Publish Date

May 12, 2026

Modified Date

May 19, 2026

Score Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected Versions