CVE-2025-66560

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.

Workarounds

For versions without the fix applied, it is recommended to implement a health check that monitors the status and saturation of the worker thread pool. This helps detect abnormal thread retention early and allows operators to take corrective action before the application’s responsiveness is impacted.

Credits

CVE reported by Shaswata Jash, Nokia

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

CVE-2025-66560 has a CVSS score of 5.9 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.20.5, 3.27.2, 3.31.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-66560? CVE-2025-66560 is a medium-severity allocation of resources without limits or throttling vulnerability in io.quarkus:quarkus-rest (maven), affecting versions < 3.20.5. It is fixed in 3.20.5, 3.27.2, 3.31.0. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. How severe is CVE-2025-66560? CVE-2025-66560 has a CVSS score of 5.9 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of io.quarkus:quarkus-rest are affected by CVE-2025-66560? io.quarkus:quarkus-rest (maven) versions < 3.20.5 is affected.
4. Is there a fix for CVE-2025-66560? Yes. CVE-2025-66560 is fixed in 3.20.5, 3.27.2, 3.31.0. Upgrade to this version or later.
5. Is CVE-2025-66560 exploitable, and should I be worried? Whether CVE-2025-66560 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-66560 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-66560?
   • Upgrade io.quarkus:quarkus-rest to 3.20.5 or later
   • Upgrade io.quarkus:quarkus-rest to 3.27.2 or later
   • Upgrade io.quarkus:quarkus-rest to 3.31.0 or later