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CVE-2025-66560

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

5.9 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.38%Up 0.3 points since Jan 8, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.9

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

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.

Record
CVE-2025-66560
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-770
Updated
2026-11-02
EUVDEUVD-2026-1178 5.9

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.

Record
EUVD-2026-1178
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-5rfx-cp42-p624 5.9

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

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

Record
GHSA-5rfx-cp42-p624
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-770
Updated
2026-11-02
NVD 5.9

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.

Record
CVE-2025-66560
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-770
Updated
2026-11-02
OSV 5.9

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

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.

Record
CVE-2025-66560
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-770
Updated
2026-11-02
OSVGHSA-5rfx-cp42-p624 5.9

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

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

Record
GHSA-5rfx-cp42-p624
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-770
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
io.quarkus:quarkus-rest
Maven
before 3.20.5
3.20.5
io.quarkus:quarkus-rest
Maven
3.21.0 up to 3.27.2
3.27.2
io.quarkus:quarkus-rest
Maven
3.30.0 up to 3.31.0
3.31.0
io.quarkus:quarkus-rest
Maven
before 3.20.5, plus listed versions
3.10.03.10.0.CR13.10.13.10.23.11.0
Show 45 moreShow less
3.11.0.CR13.11.13.11.23.11.33.12.03.12.0.CR13.12.13.12.23.12.33.13.03.13.0.CR13.13.13.13.23.13.33.14.03.14.0.CR13.14.13.14.23.14.33.14.43.15.03.15.0.CR13.15.13.15.23.15.33.15.3.13.15.43.15.53.15.63.15.6.13.15.6.23.15.73.16.03.16.0.CR13.16.13.16.23.16.33.16.43.17.03.17.0.CR13.17.13.17.23.17.33.17.43.17.5
3.20.5
io.quarkus:quarkus-rest
Maven
3.21.0 up to 3.27.2, plus listed versions
3.21.13.21.23.21.33.21.43.22.0
Show 32 moreShow less
3.22.0.CR13.22.13.22.23.22.33.23.03.23.0.CR13.23.13.23.23.23.33.23.43.24.03.24.0.CR13.24.13.24.23.24.33.24.43.24.53.25.03.25.0.CR13.25.13.25.23.25.33.25.43.26.03.26.0.CR13.26.13.26.23.26.33.26.43.27.03.27.0.CR13.27.1
3.27.2
io.quarkus:quarkus-rest
Maven
3.30.0 up to 3.31.0, plus listed versions
3.30.13.30.23.30.33.30.43.30.5
Show 4 moreShow less
3.30.63.30.73.30.83.31.0.CR1
3.31.0

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-66560 is a medium vulnerability (CVSS 5.9) in Quarkus, published January 7, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.38%, the 32nd percentile. Fixed in io.quarkus:quarkus-rest 3.20.5.

References

This page doesn't list everything

Left out here: 31 versions. The JSON record has them.

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