CVE-2025-66560
MEDIUMCVE-2025-66560 is a medium-severity (CVSS 5.9) CWE-770 vulnerability in io.quarkus:quarkus-rest. O3 Security confirms whether CVE-2025-66560 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Quarkus REST has potential worker thread starvation when HTTP connection is closed while waiting to write
Real-World Exposure
io.quarkus:quarkus-rest☕io.quarkus:quarkus-rest☕io.quarkus:quarkus-restReal-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
Quarkus is a Cloud Native, (Linux) Container First framework for writing Java applications. Prior to versions 3.31.0, 3.27.2, and 3.20.5, a vulnerability exists in the HTTP layer of Quarkus REST related to response handling. When a response is being written, the framework waits for previously written response chunks to be fully transmitted before proceeding. If the client connection is dropped during this waiting period, the associated worker thread is never released and becomes permanently blocked. Under sustained or repeated occurrences, this can exhaust the available worker threads, leading to degraded performance, or complete unavailability of the application. This issue has been patched in versions 3.31.0, 3.27.2, and 3.20.5. A workaround involves implementing a health check that monitors the status and saturation of the worker thread pool to detect abnormal thread retention early.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.quarkus:quarkus-rest | all versions | 3.20.5 |
| ☕Maven | io.quarkus:quarkus-rest | ≥ 3.21.0&&< 3.27.2 | 3.27.2 |
| ☕Maven | io.quarkus:quarkus-rest | ≥ 3.30.0&&< 3.31.0 | 3.31.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.quarkus:quarkus-rest. 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 io.quarkus:quarkus-rest to 3.20.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-66560 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-2025-66560 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-2025-66560. 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-2025-66560 in your dependencies?
O3 detects CVE-2025-66560 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.