CVE-2025-3631 Overview
A Use After Free vulnerability exists in IBM MQ 9.3 and 9.4 that allows a remote attacker to cause a denial of service condition. When an IBM MQ Client connects to an MQ Queue Manager, it can trigger a SIGSEGV (segmentation fault) in the AMQRMPPA channel process, causing immediate termination of the process and disrupting message queue operations.
Critical Impact
Remote attackers can exploit this vulnerability to crash the AMQRMPPA channel process without authentication, potentially disrupting critical enterprise messaging infrastructure and causing service outages.
Affected Products
- IBM MQ Appliance 9.3 (LTS and Continuous Delivery)
- IBM MQ Appliance 9.4 (LTS and Continuous Delivery)
Discovery Timeline
- July 11, 2025 - CVE-2025-3631 published to NVD
- July 23, 2025 - Last updated in NVD database
Technical Details for CVE-2025-3631
Vulnerability Analysis
This vulnerability is classified as CWE-416 (Use After Free), a memory corruption flaw that occurs when a program continues to reference memory after it has been freed. In the context of IBM MQ, the AMQRMPPA channel process improperly handles memory during client connection operations. When a malformed or specially crafted connection request is processed, the channel process attempts to access memory that has already been deallocated, resulting in a segmentation fault (SIGSEGV) that terminates the process.
The vulnerability is particularly concerning for enterprise environments because IBM MQ is commonly used as critical messaging middleware for business applications, financial transactions, and inter-system communications. A successful exploit could disrupt message processing across an entire organization's infrastructure.
Root Cause
The root cause is a Use After Free condition in the AMQRMPPA channel process. This process handles message passing architecture (MPA) connections from IBM MQ clients. During specific client connection scenarios, the memory management logic fails to properly track allocated memory references, leading to a dangling pointer that is subsequently dereferenced after the memory has been freed.
Attack Vector
The attack is network-based and can be executed remotely without requiring authentication or user interaction. An attacker needs network access to the IBM MQ Queue Manager port to send malicious connection requests. The vulnerability resides in the client connection handling path, meaning any entity capable of initiating MQ client connections can potentially trigger the crash.
The denial of service condition occurs when:
- A malicious or malformed IBM MQ Client connection is initiated
- The AMQRMPPA channel process processes the connection request
- Memory handling errors cause a use-after-free condition
- The SIGSEGV signal terminates the channel process
Detection Methods for CVE-2025-3631
Indicators of Compromise
- Unexpected termination of AMQRMPPA channel processes with SIGSEGV signals
- Core dump files generated by crashing MQ processes
- Repeated channel process restarts in IBM MQ error logs
- Connection failures reported by legitimate MQ clients following process crashes
Detection Strategies
- Monitor IBM MQ error logs for SIGSEGV or segmentation fault entries related to the AMQRMPPA process
- Configure alerting for abnormal MQ channel process restarts or failures
- Implement network monitoring to detect unusual connection patterns to MQ Queue Manager ports
- Review system logs for core dump generation events associated with MQ processes
Monitoring Recommendations
- Enable detailed logging on IBM MQ Queue Managers to capture connection-level events
- Deploy network intrusion detection rules to monitor traffic on IBM MQ listener ports (typically 1414)
- Implement process monitoring to track AMQRMPPA process health and restart frequency
- Configure SIEM integration to correlate MQ process crashes with network connection events
How to Mitigate CVE-2025-3631
Immediate Actions Required
- Apply the latest security patches from IBM as soon as possible
- Review and restrict network access to IBM MQ Queue Manager ports using firewall rules
- Implement network segmentation to limit which systems can initiate MQ client connections
- Monitor for abnormal connection attempts and channel process failures
Patch Information
IBM has released security advisories addressing this vulnerability. Administrators should consult the official IBM support documentation for patching guidance:
Upgrade to the patched versions of IBM MQ Appliance 9.3 and 9.4 as specified in the vendor advisories.
Workarounds
- Restrict network access to MQ Queue Manager ports to trusted IP addresses only
- Implement TLS authentication for all client connections to limit anonymous access
- Deploy load balancers or proxies that can filter malformed connection attempts
- Consider temporarily disabling non-essential channels until patches can be applied
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
