CVE-2020-1941: Apache ActiveMQ XSS Vulnerability

CVE-2020-1941 Overview

CVE-2020-1941 is a Cross-Site Scripting (XSS) vulnerability affecting the Apache ActiveMQ web console administration GUI. The vulnerability exists in versions 5.0.0 through 5.15.11, specifically in the view that displays queue contents. Attackers can inject malicious scripts that execute in the context of authenticated administrator sessions, potentially leading to session hijacking, credential theft, or unauthorized administrative actions.

Critical Impact

Authenticated administrators viewing queue contents may unknowingly execute attacker-controlled JavaScript, enabling session hijacking and unauthorized access to the message broker infrastructure.

Affected Products

• Apache ActiveMQ 5.0.0 to 5.15.11
• Oracle Communications Diameter Signaling Router
• Oracle Communications Element Manager 8.1.1, 8.2.0, 8.2.1
• Oracle Communications Session Report Manager 8.1.1, 8.2.0, 8.2.1
• Oracle Communications Session Route Manager 8.1.1, 8.2.0, 8.2.1
• Oracle Enterprise Repository 11.1.1.7.0
• Oracle FlexCube Private Banking 12.0.0, 12.1.0

Discovery Timeline

• May 14, 2020 - CVE-2020-1941 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-1941

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation). The Apache ActiveMQ web console fails to properly sanitize user-controlled input when rendering queue contents in the administrative interface. When an administrator navigates to the queue listing view, message data is displayed without adequate encoding, allowing embedded JavaScript to execute within the browser context.

The attack requires user interaction, as an administrator must view the malicious queue content through the web console. However, since ActiveMQ is commonly used in enterprise messaging infrastructures, compromising an administrator session could provide attackers with significant access to sensitive message flows and system configurations.

Root Cause

The root cause is insufficient input validation and output encoding in the web console's queue content rendering functionality. The JSP templates or servlet code responsible for displaying queue messages do not properly escape HTML special characters or JavaScript content before rendering them in the browser. This allows attackers who can inject messages into monitored queues to embed malicious scripts that execute when administrators view the queue contents.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker must first be able to send messages to a queue monitored by ActiveMQ administrators. The attacker crafts a message containing malicious JavaScript payloads embedded within message properties or body content. When an administrator accesses the web console and views the queue contents, the malicious script executes in the administrator's browser session.

The exploitation flow involves: (1) attacker sends specially crafted message to target queue, (2) administrator logs into ActiveMQ web console, (3) administrator navigates to queue view containing malicious message, (4) browser renders unsanitized content and executes attacker's JavaScript, (5) attacker can steal session cookies, perform administrative actions, or redirect the user to phishing pages.

Detection Methods for CVE-2020-1941

Indicators of Compromise

• Unusual JavaScript or HTML tags appearing in ActiveMQ queue message contents
• Unexpected outbound connections from systems accessing the ActiveMQ web console
• Session cookie exfiltration attempts to external domains
• Administrative actions performed without corresponding legitimate administrator activity

Detection Strategies

• Monitor web console access logs for requests containing encoded script tags or JavaScript event handlers
• Implement Content Security Policy (CSP) headers to detect and block inline script execution attempts
• Deploy web application firewalls (WAF) configured to detect XSS patterns in HTTP traffic to the ActiveMQ console
• Review queue message contents for suspicious payloads containing HTML or script elements

Monitoring Recommendations

• Enable detailed audit logging for ActiveMQ web console access and administrative actions
• Configure SIEM alerts for potential XSS indicators in web server logs serving the ActiveMQ console
• Monitor for anomalous administrator session behavior that may indicate session hijacking

How to Mitigate CVE-2020-1941

Immediate Actions Required

• Upgrade Apache ActiveMQ to version 5.15.12 or later which contains the security fix
• Apply Oracle Critical Patch Updates if using affected Oracle products (see Oracle CPU July 2020 Alert)
• Restrict network access to the ActiveMQ web console to trusted administrative networks only
• Implement Content Security Policy headers to mitigate XSS impact

Patch Information

Apache has addressed this vulnerability in ActiveMQ versions after 5.15.11. Organizations should upgrade to the latest stable release. For detailed patch information, refer to the Apache ActiveMQ CVE-2020-1941 Advisory.

Oracle has released patches for affected Oracle products through multiple Critical Patch Updates. Organizations using Oracle Communications Element Manager, Session Report Manager, Session Route Manager, Diameter Signaling Router, Enterprise Repository, or FlexCube Private Banking should apply the relevant Oracle CPU updates from Oracle CPU April 2021 Alert or Oracle CPU July 2021 Alert.

Workarounds

• Disable or restrict access to the ActiveMQ web console if not required for operations
• Implement network segmentation to limit who can access the web console interface
• Use a reverse proxy with XSS filtering capabilities in front of the ActiveMQ web console
• Train administrators to avoid viewing untrusted queue contents until patches are applied

# Example: Restrict ActiveMQ web console access via firewall
# Allow only trusted admin network to access web console (default port 8161)
iptables -A INPUT -p tcp --dport 8161 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8161 -j DROP