CVE-2026-42253: Apache ActiveMQ, Apache ActiveMQ Web: HTTP Response Header Injection via JMS Message Properties

["Christopher L. Shannon" <cshannon () apache org>]

Severity: important 

Affected versions:

- Apache ActiveMQ (org.apache.activemq:apache-activemq) before 5.19.7
- Apache ActiveMQ (org.apache.activemq:apache-activemq) 6.0.0 before 6.2.6
- Apache ActiveMQ Web (org.apache.activemq:activemq-web) before 5.19.7
- Apache ActiveMQ Web (org.apache.activemq:activemq-web) 6.0.0 before 6.2.6

Description:

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Apache ActiveMQ, 
Apache ActiveMQ Web.

The MessageServlet in the ActiveMQ web console API copies every JMS message
property into an HTTP response header without any validation. This can allow overwriting and injecting security headers 
by setting them on JMS messages that are returned by the servlet.

This issue affects Apache ActiveMQ: before 5.19.7, from 6.0.0 before 6.2.6; Apache ActiveMQ Web: before 5.19.7, from 
6.0.0 before 6.2.6.

Users are recommended to upgrade to version 5.19.7 or 6.2.6, which fixes the issue. The MessageServlet has now been 
deprecated and disabled by default.

Credit:

Vishal Shukla (finder)
pyn3rd (finder)
uname (finder)
4ra1n (finder)

References:

https://activemq.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-42253