Is CVE-2026-40466 actively exploited?

Yes. CVE-2026-40466 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, which means exploitation in the wild has been confirmed.

Can CVE-2026-40466 be exploited remotely?

Yes. CVE-2026-40466 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-40466?

CVE-2026-40466 has a CVSS score of 8.8 (HIGH).

HOME VULNERABILITIESCVE-2026-40466

HIGHCISA KEVIN THE WILD

CVE-2026-40466

CWE-20Published: April 24, 2026· Updated: Apr 27, 2026

8.8

CVSS v3.1

EPSS:0.21%probability of exploitation in 30 daysPercentile:42.8th

Official Description

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.

NVD Source

Technical Analysis

CVE-2026-40466 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.8.

CISA has added CVE-2026-40466 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.