CVE-2025-27533
📋 TL;DR
This vulnerability in Apache ActiveMQ allows attackers to cause denial of service by sending specially crafted OpenWire commands that trigger excessive memory allocation. It affects ActiveMQ brokers not using mutual TLS connections, potentially crashing the broker and disrupting dependent applications. Users running affected versions without proper validation are at risk.
💻 Affected Systems
- Apache ActiveMQ
📦 What is this software?
Activemq by Apache
Activemq by Apache
Activemq by Apache
Activemq by Apache
⚠️ Risk & Real-World Impact
Worst Case
Complete broker crash due to memory exhaustion, causing extended service disruption for all dependent applications and requiring manual restart.
Likely Case
Broker becomes unresponsive or crashes under attack, causing temporary service disruption until memory is freed or broker is restarted.
If Mitigated
Minimal impact with proper memory limits and monitoring; broker may experience temporary performance degradation but remains operational.
🎯 Exploit Status
Exploitation requires network access to ActiveMQ broker port (typically 61616 for OpenWire). No public exploit code identified yet.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.1.6+, 5.19.0+, 5.18.7+, 5.17.7+, or 5.16.8+
Vendor Advisory: https://lists.apache.org/thread/8hcm25vf7mchg4zbbhnlx2lc5bs705hg
Restart Required: Yes
Instructions:
1. Download patched version from Apache ActiveMQ website. 2. Stop ActiveMQ service. 3. Backup configuration and data. 4. Install new version. 5. Restore configuration if needed. 6. Start ActiveMQ service. 7. Verify functionality.
🔧 Temporary Workarounds
Enable Mutual TLS
allConfigure mutual TLS authentication for all client connections to prevent exploitation.
Configure ActiveMQ transportConnector with needClientAuth=true in activemq.xml
Network Segmentation
linuxRestrict network access to ActiveMQ broker ports to trusted sources only.
iptables -A INPUT -p tcp --dport 61616 -s trusted_ip -j ACCEPT
iptables -A INPUT -p tcp --dport 61616 -j DROP
🧯 If You Can't Patch
- Implement mutual TLS authentication for all client connections
- Apply strict network access controls to limit connections to trusted sources only
🔍 How to Verify
Check if Vulnerable:
Check ActiveMQ version and compare against affected ranges. Review if mutual TLS is configured.Check Version:
grep 'ActiveMQ' /opt/activemq/activemq.log | head -1 or check web console at http://localhost:8161Verify Fix Applied:
Confirm ActiveMQ version is 6.1.6+, 5.19.0+, 5.18.7+, 5.17.7+, or 5.16.8+. Test with monitoring for memory allocation anomalies.📡 Detection & Monitoring
Log Indicators:
- Unusual memory allocation errors
- OutOfMemoryError in logs
- Broker restart events without clear cause
Network Indicators:
- Unusual volume of OpenWire traffic to broker port 61616
- Connection attempts from unexpected sources
SIEM Query:
source="activemq.log" ("OutOfMemory" OR "memory allocation" OR "excessive")