CVE-2026-40466

Improper Input Validation, Improper Control of Generation of Code ('Code Injection') vulnerability in Apache ActiveMQ Broker, Apache ActiveMQ All, Apache ActiveMQ.

An authenticated attacker may bypass the fix in CVE-2026-34197 by adding a connector using an HTTP Discovery transport via BrokerView.addNetworkConnector or BrokerView.addConnector through Jolokia if the activemq-http module is on the classpath.
A malicious HTTP endpoint can return a VM transport through the HTTP URI which will bypass the validation added in CVE-2026-34197. The attacker can then use the VM transport's brokerConfig parameter to load a remote Spring XML application context using ResourceXmlApplicationContext.
Because Spring's ResourceXmlApplicationContext instantiates all singleton beans before the BrokerService validates the configuration, arbitrary code execution occurs on the broker's JVM through bean factory methods such as Runtime.exec().

This issue affects Apache ActiveMQ Broker: before 5.19.6, from 6.0.0 before 6.2.5; Apache ActiveMQ All: before 5.19.6, from 6.0.0 before 6.2.5; Apache ActiveMQ: before 5.19.6, from 6.0.0 before 6.2.5.

Users are recommended to upgrade to version 5.19.6 or 6.2.5, which fixes the issue.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2026-40466 has a CVSS score of 8.8 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.19.6, 6.2.5); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-40466? CVE-2026-40466 is a high-severity improper input validation vulnerability in org.apache.activemq:apache-activemq (maven), affecting versions < 5.19.6. It is fixed in 5.19.6, 6.2.5. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2026-40466? CVE-2026-40466 has a CVSS score of 8.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2026-40466?
   • org.apache.activemq:apache-activemq (maven) (versions < 5.19.6)
   • org.apache.activemq:activemq-all (maven) (versions < 5.19.6)
   • org.apache.activemq:activemq-broker (maven) (versions < 5.19.6)
4. Is there a fix for CVE-2026-40466? Yes. CVE-2026-40466 is fixed in 5.19.6, 6.2.5. Upgrade to this version or later.
5. Is CVE-2026-40466 exploitable, and should I be worried? Whether CVE-2026-40466 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-40466 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-40466?
   • Upgrade org.apache.activemq:apache-activemq to 5.19.6 or later
   • Upgrade org.apache.activemq:activemq-all to 5.19.6 or later
   • Upgrade org.apache.activemq:activemq-broker to 5.19.6 or later
   • Upgrade org.apache.activemq:apache-activemq to 6.2.5 or later
   • Upgrade org.apache.activemq:activemq-all to 6.2.5 or later
   • Upgrade org.apache.activemq:activemq-broker to 6.2.5 or later