CVE-2021-20289
MEDIUMExposure of class information in RESTEasy
Blast Radius
org.jboss.resteasy:resteasy-core☕org.jboss.resteasy:resteasy-core☕org.jboss.resteasy:resteasy-coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
A flaw was found in RESTEasy in all versions of RESTEasy up to 4.6.0.Final. The endpoint class and method names are returned as part of the exception response when RESTEasy cannot convert one of the request URI path or query values to the matching JAX-RS resource method's parameter value. The highest threat from this vulnerability is to data confidentiality.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.jboss.resteasy:resteasy-core | ≥ 4.6.0&&< 4.6.1 | 4.6.1 |
| ☕Maven | org.jboss.resteasy:resteasy-core | ≥ 4.0.0&&< 4.5.10 | 4.5.10 |
| ☕Maven | org.jboss.resteasy:resteasy-core | ≥ 3.0.0&&< 3.16.0 | 3.16.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jboss.resteasy:resteasy-core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.jboss.resteasy:resteasy-core to 4.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-20289 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2021-20289 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2021-20289. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2021-20289 in your dependencies?
O3 detects CVE-2021-20289 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.