CVE-2026-42498: Apache Tomcat: WebSocket authentication header exposure

[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 9.0.2 through 9.0.117
- Apache Tomcat 8.5.24 through 8.5.100
- Apache Tomcat 7.0.83 through 7.0.109

Description:

Exposure of HTTP Authentication Header to unexpected hosts during 
WebSocket authentication vulnerability 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 9.0.2 through 9.0.117, from 8.5.24 
through 8.5.100, from 7.0.83 through 7.0.109.

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

Credit:

lokerxx (finder)

References:

https://lists.apache.org/thread/n61zwf75jrv09rz90j4jssncm244bwdb
https://tomcat.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-42498