UndertowApplication · Redhat
CVE-2017-7559
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 · uneditedIn Undertow 2.x before 2.0.0.Alpha2, 1.4.x before 1.4.17.Final, and 1.3.x before 1.3.31.Final, it was found that the fix for CVE-2017-2666 was incomplete and invalid characters are still allowed in the query string and path parameters. This could be exploited, in conjunction with a proxy that also permitted the invalid characters but with a different interpretation, to inject data into the HTTP response. By manipulating the HTTP response the attacker could poison a web-cache, perform an XSS attack, or obtain sensitive information from requests other than their own.
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 confidenceUndertow HTTP server versions 1.3.x before 1.3.31.Final, 1.4.x before 1.4.17.Final, and 2.x before 2.0.0.Alpha2 contain an incomplete fix for CVE-2017-2666. The patch fails to properly block invalid characters in query strings and path parameters, allowing attackers to inject data into HTTP responses by leveraging proxies with different character interpretation. This enables web cache poisoning, XSS attacks, and cross-request information disclosure.
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
UndertowApplication
>= 1.3.0, < 1.3.31>= 1.4.0, < 1.4.17= 2.0.0CVSS 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
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
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.
-
Identify Undertow versionLocate the Undertow JAR file or dependency declaration (pom.xml, build.gradle, MANIFEST.MF) and note the exact version numberAffected if Version is 1.3.x before 1.3.31.Final, 1.4.x before 1.4.17.Final, or exactly 2.0.0
-
Confirm Undertow HTTP listener is in useCheck server configuration files (undertow.xml, standalone.xml, or application code) for Undertow-based HTTP connector or servlet container initializationAffected if The application uses Undertow as its HTTP server with query string and path parameter processing enabled
-
Verify request parameter parsing behaviorSend an HTTP request with non-standard characters (such as null bytes or control characters) in the query string or path and observe how the server handles themAffected if Invalid or non-standard characters in query strings or path parameters are not rejected or sanitized, allowing them to pass through to the response
-
Check for reverse proxy deploymentInspect network configuration to determine if Undertow is deployed behind a reverse proxy, load balancer, or caching serverAffected if A reverse proxy is present and may interpret character encoding differently than Undertow, enabling the cache poisoning or response injection attack vector
You are affected if your Undertow version falls within the vulnerable ranges AND your server processes HTTP query strings or path parameters with the flawed character handling, especially when behind a proxy.
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 data1.3.311.4.17
Upgrade Undertow to version 1.3.31.Final, 1.4.17.Final, or 2.0.0.Alpha2 or later. Additionally, review and validate any reverse proxy configurations to ensure consistent handling of non-standard characters in HTTP requests.
Fix this in Undertow
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-7559 — 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-2017-7559 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data