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Fencer Vulns
medium 5.9

CVE-2025-66560 json

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

published 2026-01-07 10 mo ago modified 2026-10-07 33 d ago also EUVD-2026-1178 , GHSA-5rfx-cp42-p624

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven io.quarkus:quarkus-rest 3.20.5, 3.27.2, 3.31.0
  • io.quarkus quarkus-rest 3.20.5, 3.27.2, 3.31.0
  • quarkus quarkus 3.20.5, 3.27.2, 3.31.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-66560 updated cvss 5.9

io.quarkus/quarkus-rest: Quarkus REST Worker Thread Exhaustion Vulnerability

  • Red Hat Cryostat 4 quarkus-rest Red Hat build of Debezium 3 quarkus-rest Red Hat JBoss Enterprise Application Platform 8 quarkus-rest Red Hat JBoss Enterprise Application Platform Expansion Pack quarkus-rest Red Hat OpenShift Container Platform 4 openshift4/insights-runtime-exporter-rhel9, openshift4/insights-runtime-extractor-rhel9 Red Hat streams for Apache Kafka 2 quarkus-rest
    +1 more products
    Red Hat streams for Apache Kafka 3 quarkus-rest
    affected: workaround, no fix available “Fix deferred”
  • Red Hat build of Quarkus 3.20.5.redhat quarkus-rest 3.20.5.redhat-00001
    fixed: vendor fix RHSA-2026:1899
  • Red Hat build of Quarkus 3.27.2.redhat quarkus-rest 3.27.2.redhat-00001
    fixed: vendor fix RHSA-2026:1965
  • Red Hat build of Quarkus 3.20.5.redhat jna 5.8.0, lit 3.2.1, bson 5.3.1, db2 1.20.6, h2 2.3.230, y18n 5.0.8, +1015 more Red Hat build of Quarkus 3.27.2.redhat jna 5.8.0, bson 5.5.1, db2 1.21.4, h2 2.3.230, y18n 5.0.8, cliui 8.0.1, +1004 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
10 mo ago

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
maven io.quarkus:quarkus-rest
<3.20.5
>=3.21.0, <3.27.2
>=3.30.0, <3.31.0
3.20.5
3.27.2
3.31.0

Affected products

  • quarkusio quarkus

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.