UndertowApplication · Redhat
CVE-2017-2666
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 · uneditedIt was discovered in Undertow that the code that parsed the HTTP request line permitted invalid characters. 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's HTTP request line parser accepts invalid characters that can be interpreted differently by reverse proxies. This HTTP response injection vulnerability allows attackers to manipulate responses for cache poisoning, XSS, or session hijacking by injecting malicious content that appears to be from the server.
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
all versions
Jboss Enterprise Application PlatformApplication
= 7.0.0= 7.1.0
Debian LinuxOperating system
= 9.0= 10.0CVSS 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
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/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.
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Identify if Undertow is serving HTTP trafficRun 'netstat -tlnp' or 'ss -tlnp' and look for Java processes listening on ports 80 or 443, or check your application server configuration for Undertow as the web server.Affected if Undertow is handling HTTP requests and there is a reverse proxy in front of it
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Determine the Undertow versionCheck the Undertow JAR file version in your deployment, typically found in the lib or modules directory, or query the server for HTTP response headers using 'curl -I http://localhost:8080' if accessible.Affected if The installed Undertow version is any version (all versions are affected)
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Determine the JBoss EAP version if applicableCheck the JBoss EAP installation by reviewing the 'jboss-as.jar', 'jboss-modules.jar', or running 'grep -r "jboss" startup scripts' to identify version 7.0.0 or 7.1.0.Affected if JBoss Enterprise Application Platform version 7.0.0 or 7.1.0 is in use with Undertow as the web server
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Verify if a reverse proxy exists in the architectureReview network architecture diagrams, load balancer configurations, or web server configurations (nginx, Apache, HAProxy) to determine if any reverse proxy sits in front of the Undertow server.Affected if A reverse proxy is present and may interpret invalid HTTP characters differently than Undertow
You are affected if Undertow (any version) or JBoss EAP 7.0.0/7.1.0 is serving HTTP traffic behind a reverse proxy that could interpret invalid HTTP request characters differently.
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 dataUpgrade Undertow to a version that rejects invalid HTTP characters, and ensure any reverse proxies in the infrastructure also properly validate and normalize HTTP request characters to prevent interpretation mismatches.
Fix this in Undertow
Scoped from the published advisory
- Consultation6.0 h
- Implementation8.0 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 $7,296.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-2666 — 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-2017-2666 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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