CVE-2023-5676 Overview
CVE-2023-5676 is a race condition vulnerability in Eclipse OpenJ9 before version 0.41.0 that can cause the JVM to enter an infinite busy hang on a spinlock or trigger a segmentation fault. This occurs when a shutdown signal (SIGTERM, SIGINT, or SIGHUP) is received before the JVM has completed its initialization process.
Critical Impact
Applications running on affected Eclipse OpenJ9 versions may become completely unresponsive or crash when receiving termination signals during startup, potentially causing denial of service in containerized environments, orchestration systems, or any scenario where rapid JVM lifecycle management is required.
Affected Products
- Eclipse OpenJ9 versions prior to 0.41.0
Discovery Timeline
- 2023-11-15 - CVE-2023-5676 published to NVD
- 2025-11-03 - Last updated in NVD database
Technical Details for CVE-2023-5676
Vulnerability Analysis
This vulnerability stems from a race condition (CWE-362) combined with signal handler race conditions (CWE-364) in the Eclipse OpenJ9 JVM's signal handling mechanism during initialization. The vulnerability requires network access and high attack complexity to exploit, as the attacker must precisely time the delivery of a shutdown signal during the narrow window when the JVM is initializing but not yet ready to properly handle termination requests.
When exploited, the vulnerability results in a complete denial of service condition. The JVM either enters an infinite busy hang state where it continuously spins on a lock without making progress, or it crashes with a segmentation fault. Both outcomes render the Java application unavailable and may require manual intervention to recover.
Root Cause
The root cause is a classic Time-of-Check Time-of-Use (TOCTOU) race condition in the signal handling infrastructure. During JVM initialization, there exists a state where signal handlers are registered but the underlying data structures or locks they depend on are not yet fully initialized. When a shutdown signal arrives in this vulnerable window, the signal handler attempts to access these uninitialized or partially initialized resources, leading to either deadlock (infinite spinlock) or memory access violations (segmentation fault).
Attack Vector
The attack vector requires the ability to send process signals to the JVM during its startup phase. In practical scenarios, this could be exploited in:
- Container orchestration environments where rapid scaling operations may send termination signals to newly spawning JVM instances
- Cloud platforms with aggressive health checks that may terminate slow-starting applications
- System management scenarios where administrators send signals during batch JVM restarts
- Automated deployment pipelines where timing conditions may cause premature termination signals
The vulnerability can be triggered by sending any of the standard Unix shutdown signals (SIGTERM, SIGINT, or SIGHUP) to a JVM process that is still in its initialization phase. The precise timing required makes automated exploitation challenging, but in high-throughput environments with many JVM instances starting and stopping, the probability of triggering the condition increases significantly.
Detection Methods for CVE-2023-5676
Indicators of Compromise
- JVM processes stuck in an unresponsive state consuming CPU cycles without making progress
- Unexpected segmentation faults in OpenJ9 JVM processes during startup
- Java applications failing to start or respond after receiving deployment signals
- Core dumps or crash reports indicating signal handler issues during JVM initialization
Detection Strategies
- Monitor for JVM processes that remain in initialization state longer than expected baseline
- Implement health checks that track JVM startup completion events
- Review system logs for segmentation fault messages correlated with JVM startups
- Track container restart loops that may indicate repeated crash-restart cycles due to this vulnerability
Monitoring Recommendations
- Configure alerting for JVM processes consuming high CPU without completing initialization
- Monitor container orchestration logs for pods stuck in CrashLoopBackOff states running OpenJ9
- Implement startup probes in Kubernetes environments to detect JVMs that fail to initialize properly
- Review application metrics for unusual patterns of startup failures during high-deployment activity periods
How to Mitigate CVE-2023-5676
Immediate Actions Required
- Upgrade Eclipse OpenJ9 to version 0.41.0 or later which contains the fix for this vulnerability
- Review deployment scripts and orchestration configurations to ensure adequate startup time before health checks
- Consider implementing startup delays or grace periods in container environments running affected versions
- Inventory all applications using Eclipse OpenJ9 to identify systems requiring updates
Patch Information
The vulnerability has been addressed in Eclipse OpenJ9 version 0.41.0. The fix is documented in the GitHub Pull Request #18085. Additional information about the CVE assignment can be found in the GitLab CVE Assignment Issue. Organizations using NetApp products should also consult the NetApp Security Advisory for product-specific guidance.
Workarounds
- Implement startup scripts that delay signal handlers until JVM initialization is confirmed complete
- Configure container orchestration to use longer initialDelaySeconds for liveness and readiness probes
- Avoid sending termination signals to JVM processes during their startup phase when possible
- Consider using process supervisors that wait for application-level ready signals before enabling signal handling
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
