CVE-2026-50734: Apache ActiveMQ Client, Apache ActiveMQ, Apache ActiveMQ All: Pre-authentication OpenWire memory-allocation DoS during wire format negotiation

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

Severity: important 

Affected versions:

- Apache ActiveMQ Client (org.apache.activemq:activemq-client) before 5.19.8
- Apache ActiveMQ Client (org.apache.activemq:activemq-client) 6.0.0 before 6.2.7
- Apache ActiveMQ (org.apache.activemq:apache-activemq) before 5.19.8
- Apache ActiveMQ (org.apache.activemq:apache-activemq) 6.0.0 before 6.2.7
- Apache ActiveMQ All (org.apache.activemq:activemq-all) before 5.19.8
- Apache ActiveMQ All (org.apache.activemq:activemq-all) 6.0.0 before 6.2.7

Description:

Memory Allocation with Excessive Size Value vulnerability in Apache ActiveMQ Client, Apache ActiveMQ, Apache ActiveMQ 
All.

An unauthenticated network attacker can cause a broker DoS by sending a crafted WireFormatInfo frame with a malicious 
large size value. The value is not validate and causes the broker to attempt allocation during pre-auth negotiation 
which can trigger OOM and crash the broker.
This issue affects Apache ActiveMQ Client: before 5.19.8, from 6.0.0 before 6.2.7; Apache ActiveMQ: before 5.19.8, from 
6.0.0 before 6.2.7; Apache ActiveMQ All: before 5.19.8, from 6.0.0 before 6.2.7.

Users are recommended to upgrade to version 6.2.7 or 5.19.8, which fixes the issue.

Credit:

Andrej Tomci (finder)

References:

https://activemq.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-50734