CVE-2024-4027
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 · uneditedA flaw was found in Undertow. Servlets using a method that calls HttpServletRequestImpl.getParameterNames() can cause an OutOfMemoryError when the client sends a request with large parameter names. This issue can be exploited by an unauthorized user to cause a remote denial-of-service (DoS) attack.
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 exists in Undertow where calling HttpServletRequestImpl.getParameterNames() on requests containing excessively large parameter names triggers an OutOfMemoryError, allowing unauthorized remote attackers to exhaust server memory.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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 Undertow presenceSearch for undertow-core JAR files in your application lib directory, or check Maven/Gradle dependencies for 'undertow-core'. If using JBoss/WildFly, check the 'modules/system/layers/base/io/undertow' directory.Affected if Undertow is not present in your environment
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Determine Undertow versionLocate the undertow-core JAR and check its filename for version (e.g., undertow-core-2.3.x.jar), or run: jar -xf undertow-core.jar META-INF/MANIFEST.MF and inspect Implementation-Version.Affected if Version cannot be determined or is unknown
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Verify servlet request handling is enabledConfirm your application deploys servlets or REST endpoints that process HTTP requests. Check web.xml or annotation-based servlet configurations (@WebServlet, @RestController, @RequestMapping).Affected if Your application does not process HTTP requests through Undertow's HttpServletRequestImpl
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Check for parameter parsing exposureReview if your endpoints use request.getParameter(), getParameterNames(), getParameterMap(), or similar APIs that trigger parameter parsing in the query string or form body.Affected if Your application never calls getParameterNames() or similar parameter retrieval methods on HttpServletRequest
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Confirm network exposureDetermine if the vulnerable endpoints are accessible over network. Check firewall rules, load balancer configurations, and application security constraints.Affected if Affected endpoints are exposed to untrusted network traffic
You are affected if your environment runs Undertow with a vulnerable version, processes servlet requests, and exposes endpoints that could trigger getParameterNames() with large parameter names to untrusted users.
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.
From vendor dataUpdate Undertow to the latest patched version. As an interim measure, implement request/parameter size limits at the load balancer or reverse proxy level to reject requests with abnormally large parameter names before they reach the application.
- Consultation6.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,448.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2024-4027 — 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-2024-4027 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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