CVE-2026-86404 Red Hat CVE debrief

Who should care

Defenders and security teams should assess exposure to CVE-2026-86404 and prioritize remediation due to the high CVSS score and potential security issues with deserialization of all classes by default.

Why it matters

CVE-2026-86404 is a high-severity vulnerability in EAP's Artemis deserialization configuration. Defenders should assess exposure and prioritize remediation due to the potential for security issues with deserialization of all classes by default.

• Deserialization of all classes by default can lead to security issues
• High CVSS score of 8.8 indicates high severity
• Remediation is prioritized due to potential security issues

Technical summary

The EAP's Artemis deserialization configuration permits deserialization by default. ObjectMessage.getObject() uses ObjectInputStreamWithClassLoader, which implements allow-list/block-list filtering via its checkSecurity()/isTrustedType() method. However, by default both allow-list and block-list are empty. When the allow-list is empty (size == 0), isTrustedType() returns true for ALL classes. This means all classes are deserializable by default. The high CVSS score of 8.8 indicates a high severity level, and defenders should take immediate action to assess their exposure and prioritize remediation.

Defensive priority

Defenders should assess exposure and prioritize remediation due to the high CVSS score of 8.8 and the potential for security issues with deserialization of all classes by default.

Recommended defensive actions

• Assess exposure to CVE-2026-86404
• Prioritize remediation of the Artemis deserialization configuration
• Verify the allow-list and block-list configuration
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• 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

The CVE record and NVD vulnerability detail page provide information on the vulnerability, including its description, CVSS score, and references. The vulnerability is caused by the deserialization configuration of Artemis in EAP, which allows all classes to be deserialized by default. The CVE record was published on 2026-09-07T12:17:21.840Z and has not been modified since then. There are no known affected scope or additional details available. Defenders should verify the allow-list and block-list configuration and review compensating

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.