Quarkus REST has potential worker thread starvation when HTTP connection is closed while waiting to write

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2025-66560: 0.38% estimated exploitation activity in the next 30 days; percentile 32.37 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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

Published by the source

7 Jan 2026, 18:09 UTC

Last modified by the source

7 Jan 2026, 20:37 UTC

Source last checked

26 Oct 2026, 16:43 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-5rfx-cp42-p624

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# Patch Next advisory brief: CVE-2025-66560

Advisory: Quarkus REST has potential worker thread starvation when HTTP connection is closed while waiting to write
IDs: CVE-2025-66560, GHSA-5rfx-cp42-p624
Record: https://patchnext.com/advisories/cve-2025-66560 (revision 1, source checked 26 Oct 2026, 16:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: io.quarkus:quarkus-rest 3.31.0, 3.27.2, 3.20.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven io.quarkus:quarkus-rest: affected < 3.20.5; >= 3.21.0, < 3.27.2; >= 3.30.0, < 3.31.0; fixed in 3.31.0, 3.27.2, 3.20.5

## Suggested inspection (read-only)
- Maven io.quarkus:quarkus-rest: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on io.quarkus:quarkus-rest.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-5rfx-cp42-p624 (GitHub-reviewed advisory GHSA-5rfx-cp42-p624 lists affected ranges: Maven io.quarkus:quarkus-rest >=0 =3.21.0 =3.30.0 <3.31.0)

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