CVE-2026-90472 msgpack CVE debrief

Who should care

Defenders responsible for systems that use msgpack-java to deserialize data from untrusted sources should assess exposure and prioritize verification and remediation efforts. This includes operators, platform administrators, vulnerability management teams, and security teams who need to review and update msgpack-java to a patched version, review compensating controls, and implement additional monitoring and logging for deserialization failures.

Why it matters

CVE-2026-90472 is a stack overflow vulnerability in msgpack-java through 0.9.12 that can cause deserialization failures and potentially allow attackers to craft malicious data to exhaust system resources. Defenders responsible for systems that use msgpack-java to deserialize data from untrusted sources should assess exposure and prioritize verification and remediation efforts.

• Denial of service (DoS) due to deserialization failures
• Potential for attackers to craft malicious msgpack data to exhaust system resources
• Need for defenders to verify and update msgpack-java to a patched version

Technical summary

The msgpack-java library through version 0.9.12 contains a stack overflow vulnerability in the MessageUnpacker.unpackValue() method. This method recursively deserializes arrays and maps without proper nesting depth limits, allowing attackers to craft malicious msgpack data that causes a StackOverflowError during deserialization. The vulnerability can be triggered by deeply nested arrays in msgpack data. Defenders should prioritize verifying and updating msgpack-java to a version that addresses the stack overflow vulnerability, particularly in systems that deserialize msgpack data from untrusted sources.

Defensive priority

Defenders should prioritize verifying and updating msgpack-java to a version that addresses the stack overflow vulnerability, particularly in systems that deserialize msgpack data from untrusted sources.

Recommended defensive actions

• Verify msgpack-java version and update to a patched version if available
• Review and limit msgpack data deserialization from untrusted sources
• Implement additional monitoring and logging for deserialization failures
• 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 entry provide details on the stack overflow vulnerability in msgpack-java through 0.9.12. The vulnerability is triggered by deeply nested arrays in msgpack data, causing a StackOverflowError during deserialization.

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.