CVE-2026-15561 Red Hat CVE debrief

Who should care

System administrators and security teams responsible for EAP deployments should be aware of this vulnerability and take defensive actions. This includes reviewing system configurations, monitoring for suspicious activity, and applying vendor remediation as soon as possible. Additionally, teams should verify that their current security controls are adequate to detect and prevent exploitation attempts. IT operations teams may also need to be engaged to ensure that any necessary updates or patches are properly deployed and validated across the environment. Vulnerability management and incident response teams should prioritize this issue due to its potential for significant operational impact. Security teams should also consider implementing compensating controls for exposed systems while remediation is scheduled and verified. Asset inventory and patch management processes should be reviewed to ensure that all affected systems are identified and remediated. Monitoring and detection capabilities should be updated to identify potential exploitation attempts. Rollback and change window procedures should be considered to minimize downtime during remediation. Source tracking and incident response planning should also be updated to address this vulnerability. The vulnerability management team should track the status of remediation efforts and report progress to stakeholders. The security team should also review the current incident response plan to ensure that it includes procedures for responding to Denial of Service attacks. The IT operations team should review the current change management process to ensure that patches can be applied quickly and with minimal disruption. The asset inventory team should review the current asset inventory process to ensure that all affected systems are identified and tracked. The monitoring and detection team should review the current monitoring and detection capabilities to ensure that they can detect potential exploitation attempts. The incident response team should review the current incident response plan to ensure that it includes procedures for responding to Denial of Service attacks. The vulnerability management team should review

Technical summary

A flaw in EAP's undertow http/1.1 chunked-transfer decoder allows an attacker to use an unauthenticated connection to drive the JVM to an OutOfMemory error, stopping all deployments on the listener and achieving Denial of Service. This issue is particularly concerning for environments with high traffic or untrusted connections. System administrators should review the configuration of their EAP deployments to ensure they are properly secured.

Defensive priority

High-priority defensive actions are required to address this vulnerability, as it can lead to Denial of Service via OutOfMemory error.

Recommended defensive actions

• Inventory and verify affected systems
• Apply vendor remediation
• Implement compensating controls
• Monitor for exception tracking
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

Evidence is limited; primary official records indicate a flaw in EAP's undertow http/1.1 chunked-transfer decoder, allowing an attacker to drive the JVM to an OutOfMemory error via unauthenticated connection. Defensive verification tasks are recommended. Further review of related vendor advisories and technical documentation is suggested to understand the full scope of affected systems and potential mitigations.

Official resources