OOM DoS via TLS v1.3 KeyUpdate in Apache ActiveMQ <=5.19.4/6.2.4
CVE-2026-39304 Published on April 10, 2026

Apache ActiveMQ Client, Apache ActiveMQ Broker, Apache ActiveMQ All, Apache ActiveMQ: Incorrect handling of TLSv1.3 KeyUpdate can be exploited to cause DoS via OOM
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.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-39304 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Weakness Types

What is a Resource Exhaustion Vulnerability?

The software does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.

CVE-2026-39304 has been classified to as a Resource Exhaustion vulnerability or weakness.

Allocation of Resources Without Limits or Throttling

The software allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.


Products Associated with CVE-2026-39304

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2026-39304 are published in these products:

Apache ActiveMQ
 
Red Hat Jboss Fuse
 
Red Hat Amq Broker
 
Red Hat Camel Spring Boot
 
Red Hat Jboss Data Grid
 
Red Hat Enterprise Linux (RHEL)
 
Red Hat Jboss Enterprise Application Platform
 
Red Hat Jbosseapxp
 

Affected Versions

Apache Software Foundation Apache ActiveMQ Client: Apache Software Foundation Apache ActiveMQ Broker: Apache Software Foundation Apache ActiveMQ All: Apache Software Foundation Apache ActiveMQ: Red Hat Fuse 7: Red Hat AMQ Broker 7: Red Hat build of Apache Camel for Spring Boot 4: Red Hat Data Grid 8: Red Hat Enterprise Linux 8: Red Hat Enterprise Linux 9: Red Hat JBoss Enterprise Application Platform 7: Red Hat JBoss Enterprise Application Platform 8: Red Hat JBoss Enterprise Application Platform Expansion Pack:

Exploit Probability

EPSS
0.68%
Percentile
47.66%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.