CVE-2025-66560
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedQuarkus 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA denial-of-service vulnerability in Quarkus REST's HTTP layer causes worker threads to become permanently blocked when client connections drop during response transmission. The framework waits for previously written response chunks to fully transmit before proceeding, but if the connection drops during this waiting period, the associated worker thread is never released. Sustained occurrences exhaust worker threads, causing service unavailability.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 3.20.5>= 3.21.0, < 3.27.2>= 3.30.0, < 3.31.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Quarkus versionLocate the Quarkus version in your project dependency management (pom.xml, build.gradle, gradle.properties) or check the Quarkus JAR manifest/META-INF. Also check application startup logs for the Quarkus version line.Affected if The installed version falls into any of these ranges: < 3.20.5, >= 3.21.0 and < 3.27.2, or >= 3.30.0 and < 3.31.0
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Confirm Quarkus REST usageVerify that your application uses Quarkus REST (formerly RESTEasy Reactive) for HTTP endpoints. Check for the quarkus-rest dependency in your build file and confirm your application exposes HTTP endpoints via REST controllers.Affected if The application uses Quarkus REST for handling HTTP requests and responses
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Monitor worker thread behaviorDuring normal operation or load testing, observe the HTTP worker thread pool (typically the undertow or vert.x worker threads). Use JConsole, JVisualVM, or your observability platform to monitor thread states. Look for threads stuck in waiting or blocking states related to response writing.Affected if Worker threads remain in blocked/waiting state indefinitely after client disconnections during response transmission
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Check for abnormal thread pool saturationMonitor the HTTP worker thread pool utilization over time. If thread count increases and does not return to baseline, or if thread pool maxes out during normal traffic, this indicates the vulnerability may be triggered.Affected if Worker thread pool saturates and does not recover, especially during or after periods of client disconnections
You are affected if your Quarkus version is below 3.20.5, between 3.21.0-3.27.1, or between 3.30.0-3.30.x, AND your application uses Quarkus REST to serve HTTP responses where client disconnections can occur during response transmission.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped3.20.53.27.23.31.0
Upgrade Quarkus to version 3.31.0, 3.27.2, or 3.20.5 or later to patch the vulnerability. As a compensating control, implement health checks monitoring worker thread pool saturation to detect abnormal thread retention early.
Quarkus 3.31.0 (or 3.27.2/3.20.5 depending on current version branch)
- Identify the current Quarkus version in use by checking pom.xml or build configuration
- Determine which fixed version applies to your current version: if < 3.20.5 upgrade to 3.20.5; if >= 3.21.0 and < 3.27.2 upgrade to 3.27.2; if >= 3.30.0 and < 3.31.0 upgrade to 3.31.0
- Update the Quarkus version in pom.xml or build.gradle to the appropriate fixed version (recommended: 3.31.0 for the latest stable release with the fix)
- Run full test suite to verify the application functions correctly after the upgrade
- Deploy the updated application
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation2.0 h
- Testing6.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-66560 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-66560 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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