CVE-2026-95155 FasterXML CVE debrief

Who should care

Defenders responsible for applications that deserialize untrusted JSON using ObjectMapper.readValue should verify and remediate this vulnerability, especially in systems handling JSON input from untrusted sources.

Why it matters

CVE-2026-95155 is a denial-of-service vulnerability in FasterXML Jackson 1.x. Defenders should prioritize verifying and remediating this vulnerability in applications that deserialize untrusted JSON using ObjectMapper.readValue, especially in systems handling JSON input from untrusted sources.

• Denial of service through deeply nested JSON input
• Potential for elevated privileges if exploited in conjunction with other vulnerabilities
• Need for input validation and sanitization
• Verification of FasterXML Jackson 1.x version

Technical summary

FasterXML Jackson 1.x, confirmed in jackson-mapper-asl versions 1.8.3, 1.9.2, 1.9.11, 1.9.12, and 1.9.13, allows attackers to cause a denial of service by supplying deeply nested JSON input to an application that deserializes untrusted JSON using ObjectMapper.readValue. This vulnerability affects applications deserializing untrusted JSON input, particularly those handling JSON from untrusted sources. Defenders should prioritize verifying and remediating this vulnerability in applications that deserialize untrusted JSON using ObjectMapper.readValue, especially in systems handling JSON input from untrusted sources.

Defensive priority

Defenders should prioritize verifying and remediating this vulnerability in applications that deserialize untrusted JSON using ObjectMapper.readValue, especially in systems handling JSON input from untrusted sources.

Recommended defensive actions

• Verify applications that deserialize untrusted JSON using ObjectMapper.readValue are using a version of FasterXML Jackson 1.x that is not vulnerable.
• Remediate vulnerable applications by updating to a secure version of FasterXML Jackson 1.x.
• Implement input validation and sanitization for JSON input from untrusted sources.
• 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 source item provide details on the vulnerability, but do not offer specific information on exploitation or affected versions beyond jackson-mapper-asl versions 1.8.3, 1.9.2, 1.9.11, 1.9.12, and 1.9.13.

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.