CVE-2026-39304

Denial of Service via Out of Memory vulnerability in Apache ActiveMQ Client, Apache ActiveMQ Broker, Apache ActiveMQ. ActiveMQ NIO SSL transports do not correctly handle TLSv1.3 handshake KeyUpdates triggered by clients. This makes it possible for a client to rapidly trigger updates which causes the broker to exhaust all its memory in the SSL engine leading to DoS. Note: TLS versions before TLSv1.3 (such as TLSv1.2) are broken but are not vulnerable to OOM. Previous TLS versions require a full handshake renegotiation which causes a connection to hang but not OOM. This is fixed as well. This issue affects Apache ActiveMQ Client: before 5.19.4, from 6.0.0 before 6.2.4; Apache ActiveMQ Broker: before 5.19.4, from 6.0.0 before 6.2.4; Apache ActiveMQ: before 5.19.4, from 6.0.0 before 6.2.4. Users are recommended to upgrade to version 6.2.4 or 5.19.5, which fixes the issue.

Affected products

Apache Activemq, Apache Activemq Broker, Apache Activemq Client, Red Os

Apache Activemq

< 5.19.4, 6.2.4

Apache Activemq Broker

< 5.19.4, 6.2.4

Fix

Available

CVSS 3.1

7.5 HIGH

EPSS

0.9% (56th percentile)

Weakness

CWE-770, CWE-400

NVD status

Modified

Published

2026-04-10

No exploit for CVE-2026-39304 has been indexed yet. Our index is built from live traffic and upstream syncs, so this page can only say what it knows — not that no exploit exists.