CVE-2026-59878 Apache Software Foundation CVE debrief

Who should care

Organizations using Apache ActiveMQ AMQP, Apache ActiveMQ, or Apache ActiveMQ All should be aware of this denial-of-service vulnerability and take steps to mitigate it. This includes reviewing and adjusting configurations for exposed AMQP NIO connectors, monitoring for unusual traffic patterns, and implementing compensating controls to limit exposure. Security teams should prioritize upgrading to version 5.19.9, 6.2.8, or 6.3.0 to mitigate this vulnerability. Vulnerability management and security teams should track exceptions, retest remediated assets, and close the item only after evidence is documented. Operators and platform teams should confirm whether affected product deployments exist in managed environments and assign an owner for follow-up. They should also plan vendor-supported updates or mitigations through normal change control where exposure is confirmed. Asset inventory and change management processes should be reviewed to ensure accurate tracking of affected systems and changes made to mitigate the vulnerability. Compensating controls should be implemented for exposed systems while remediation is scheduled and verified. Monitoring, detection, and logs should be checked for exposed assets that need extra review. Rollback/change windows should be considered for updates and patches. Source tracking should be used to verify the status of affected systems and changes made to mitigate the vulnerability. Security teams should review compensating controls for exposed systems while remediation is scheduled and verified. They should also review relevant monitoring, detection, and logs for exposed assets that need extra review. Asset inventory and change management processes should be reviewed to ensure accurate tracking of affected systems and changes made to mitigate the vulnerability. Compensating controls should be implemented for exposed systems while remediation is scheduled and verified. Monitoring, detection, and logs should be checked for exposed assets that need extra review. Rollback/change windows should be considered for updates and patches. Source tracking should be used to verify the status of affected systems and changes made to mitigate the v

Technical summary

CVE-2026-59878 is an Improper Input Validation vulnerability in Apache ActiveMQ AMQP, Apache ActiveMQ, and Apache ActiveMQ All. A remote unauthenticated peer can trigger denial-of-service behavior by sending a frame size value, causing NIO threads to die and potentially leading to exhaustion of the NIO thread pool. The issue affects versions before 5.19.9 and from 6.0.0 before 6.2.8 for all three products.

Defensive priority

Organizations using Apache ActiveMQ AMQP, Apache ActiveMQ, or Apache ActiveMQ All should prioritize upgrading to version 5.19.9, 6.2.8, or 6.3.0 to mitigate this denial-of-service vulnerability.

Recommended defensive actions

• Upgrade to version 5.19.9, 6.2.8, or 6.3.0
• Review and adjust configurations for exposed AMQP NIO connectors
• Monitor for unusual traffic patterns
• Implement compensating controls to limit exposure
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Evidence notes

The CVE-2026-59878 record indicates an Improper Input Validation vulnerability in Apache ActiveMQ AMQP, Apache ActiveMQ, and Apache ActiveMQ All. A remote unauthenticated peer can trigger denial-of-service behavior by sending a frame size value, causing NIO threads to die and potentially leading to exhaustion of the NIO thread pool. The issue affects versions before 5.19.9 and from 6.0.0 before 6.2.8 for all three products.

Official resources