CVE-2026-41044: Apache ActiveMQ RCE Vulnerability

CVE-2026-41044 Overview

A critical code injection vulnerability has been identified in Apache ActiveMQ that allows an authenticated attacker to achieve remote code execution through a malicious broker name injection attack chain. The vulnerability stems from improper input validation in the admin web console that enables an attacker to bypass broker name validation and load a remote malicious Spring XML application context, ultimately leading to arbitrary code execution on the broker's JVM.

Critical Impact

Authenticated attackers can achieve remote code execution on Apache ActiveMQ broker servers through a chained attack involving malicious broker name injection and Spring XML context loading, potentially leading to full system compromise.

Affected Products

• Apache ActiveMQ versions before 5.19.6 and from 6.0.0 before 6.2.5
• Apache ActiveMQ Broker versions before 5.19.6 and from 6.0.0 before 6.2.5
• Apache ActiveMQ All versions before 5.19.6 and from 6.0.0 before 6.2.5

Discovery Timeline

• April 24, 2026 - CVE CVE-2026-41044 published to NVD
• April 27, 2026 - Last updated in NVD database

Technical Details for CVE-2026-41044

Vulnerability Analysis

This vulnerability is a sophisticated multi-stage attack that exploits weaknesses in Apache ActiveMQ's broker name validation mechanism combined with Spring Framework's XML application context loading behavior. The attack requires authentication to the admin web console, making it exploitable by any user with console access.

The fundamental issue lies in how ActiveMQ validates broker names during configuration. An authenticated attacker can craft a malicious broker name that passes initial validation but contains an xbean binding reference. This binding reference points to a malicious remote Spring XML application context file controlled by the attacker.

When the attacker subsequently triggers the creation of a VM transport through the DestinationView MBean by sending a specially crafted message, ActiveMQ attempts to resolve the broker name containing the xbean binding. This causes the remote Spring XML context file to be fetched and loaded.

The critical exploitation window occurs because Spring's ResourceXmlApplicationContext instantiates all singleton beans defined in the configuration before the BrokerService has a chance to validate the configuration. Attackers can define bean factory methods such as Runtime.exec() within their malicious Spring XML context, resulting in arbitrary code execution on the broker's JVM with the privileges of the ActiveMQ service account.

Root Cause

The root cause of this vulnerability is inadequate input validation of broker names in the ActiveMQ admin web console. The validation logic fails to properly sanitize or reject broker name values that contain xbean protocol bindings, allowing attackers to inject references to external resources that will be automatically loaded by the Spring Framework during context initialization.

Attack Vector

The attack is executed over the network against the ActiveMQ admin web console. An attacker must first authenticate to the console, then navigate to broker configuration functionality where they can inject a maliciously crafted broker name containing an xbean binding to an attacker-controlled Spring XML file. The attacker then uses the DestinationView MBean to send a message that triggers VM transport creation, causing the malicious context to be loaded and arbitrary code to execute.

The vulnerability mechanism involves multiple components working together: the admin console's insufficient input validation allows the malicious broker name to be stored; the VM transport system references this name during transport creation; and Spring's eager bean instantiation executes the malicious code before validation can occur. For detailed technical analysis, see the Apache ActiveMQ Security Advisory.

Detection Methods for CVE-2026-41044

Indicators of Compromise

• Unexpected outbound network connections from ActiveMQ broker processes to external hosts hosting XML files
• Broker names containing xbean: protocol references in ActiveMQ configuration
• Unusual process spawning from the ActiveMQ JVM process, particularly shell commands or system utilities
• Suspicious entries in ActiveMQ logs showing attempts to load remote Spring XML contexts

Detection Strategies

• Monitor admin web console access logs for repeated configuration changes or unusual broker naming patterns
• Implement network segmentation rules to alert on ActiveMQ brokers making outbound HTTP/HTTPS requests to untrusted hosts
• Deploy runtime application security monitoring to detect Runtime.exec() or similar dangerous method invocations from Spring context loading
• Audit JMX/MBean access logs for suspicious DestinationView operations following broker configuration changes

Monitoring Recommendations

• Enable verbose logging for ActiveMQ broker configuration changes and Spring context loading events
• Configure security information and event management (SIEM) rules to correlate admin console authentication with subsequent broker name modifications
• Implement file integrity monitoring on ActiveMQ configuration directories to detect unauthorized changes
• Monitor Java process behavior for unexpected child process creation or outbound network activity

How to Mitigate CVE-2026-41044

Immediate Actions Required

• Upgrade Apache ActiveMQ to version 5.19.6 or 6.2.5 immediately
• Restrict access to the ActiveMQ admin web console to trusted administrators only
• Implement network egress filtering to prevent ActiveMQ brokers from making outbound connections to untrusted hosts
• Review existing broker configurations for any suspicious broker names containing xbean references

Patch Information

Apache has released security patches addressing this vulnerability in ActiveMQ versions 5.19.6 and 6.2.5. Organizations should upgrade to one of these patched versions as the primary remediation. The patches implement proper validation of broker names to reject xbean protocol bindings and other potentially dangerous input patterns. See the Apache ActiveMQ Security Advisory for detailed upgrade instructions.

Workarounds

• Disable or restrict access to the ActiveMQ admin web console until patching is complete
• Implement strict network egress rules blocking outbound HTTP/HTTPS from ActiveMQ broker hosts
• Deploy a web application firewall (WAF) in front of the admin console to filter potentially malicious broker name inputs
• Use JVM security manager policies to restrict dangerous operations like Runtime.exec() from Spring context loading

# Restrict admin console access via firewall
# Allow only trusted admin workstations
iptables -A INPUT -p tcp --dport 8161 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8161 -j DROP

# Block outbound HTTP from ActiveMQ server
iptables -A OUTPUT -p tcp --dport 80 -m owner --uid-owner activemq -j DROP
iptables -A OUTPUT -p tcp --dport 443 -m owner --uid-owner activemq -j DROP