CVE-2025-66560: Quarkus

High severity, CVSS 7.5. EPSS: 0.4% chance of exploitation in the next 30 days.

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 products

• Quarkus Quarkus: before 3.20.5 (fixed in 3.20.5); from 3.21.0, before 3.27.2 (fixed in 3.27.2); from 3.30.0, before 3.31.0 (fixed in 3.31.0)

Published 2026-01-07. Last modified 2026-10-07.