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UndertowApplication · Redhat

CVE-2017-12165

HIGH · 7.5 CVSS v3.0 Published 2018-07-27
Fix available
A fix is available. Upgrade to 1.3.31 / 1.4.17 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
It was discovered that Undertow before 1.4.17, 1.3.31 and 2.0.0 processes http request headers with unusual whitespaces which can cause possible http request smuggling.

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 confidence

Undertow HTTP server versions before 1.4.17, 1.3.31, and 2.0.0 fail to properly normalize HTTP request headers containing unusual whitespace characters (e.g., tabs, vertical tabs, non-standard spaces). This inconsistency between how Undertow and intermediary proxies (load balancers, reverse proxies) parse these headers enables HTTP request smuggling attacks, potentially allowing attackers to bypass security controls, poison caches, or hijack sessions.

MitigationUpgrade Undertow to version 1.4.17, 1.3.31, 2.0.0 or later to include the header parsing fix. Verify that any upstream proxies also handle whitespace-normalized headers consistently.

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
Affected:>= 1.0.0, < 1.3.31>= 1.4.0, < 1.4.17= 2.0.0
Jboss Enterprise Application PlatformApplication
Affected:= 7.0.0= 7.1.0

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
High
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Undertow as a dependency
    Search your project dependencies (Maven pom.xml, Gradle build.gradle, or lib/ directory) for 'undertow-core' or 'undertow-servlet' artifacts, or check application server bundles for undertow JAR files
    Affected if Undertow is present as a dependency or embedded server component
  2. Locate Undertow JAR version
    Inspect the filename of undertow-core JAR in your lib/, WEB-INF/lib/, or server lib directory (e.g., undertow-core-1.4.15.jar) or run: jar -tf undertow-core.jar | grep 'META-INF/MANIFEST.MF' and read the Implementation-Version
    Affected if The JAR filename or manifest does not reveal a 1.3.31+, 1.4.17+, or 2.0.0+ version
  3. Query Undertow version programmatically
    At runtime, call Undertow.getInstance().getClass().getPackage().getImplementationVersion() or inspect org.jboss.logging.Logger.ROOT_LOGGER_ID for version strings in server logs on startup
    Affected if The logged or returned version string matches < 1.3.31, 1.4.0 to < 1.4.17, or exactly 2.0.0
  4. Check JBoss EAP version if applicable
    If running on JBoss Enterprise Application Platform, run 'standalone.sh --version' or 'domain.sh --version', or read the 'jboss-eap-*.jar' file in the installation root or check the product.conf file
    Affected if The version reported is 7.0.0 or 7.1.0
  5. Verify HTTP listener is active
    Confirm the application exposes an HTTP/HTTPS endpoint (check server configuration XML for <http-listener>, <ajp-listener>, or programmatic Undertow.builder() calls with setHandler()
    Affected if Any Undertow HTTP listener is bound and accepting requests (the vulnerability requires an active HTTP server to be exploitable)

You are affected if Undertow version is any 1.0.0 to <1.3.31, 1.4.0 to <1.4.17, or exactly 2.0.0; or if JBoss EAP is version 7.0.0 or 7.1.0, and the server exposes an HTTP endpoint.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to 1.3.31 / 1.4.17 or later
Fixed in 1.3.311.4.17
Interim mitigation

Upgrade Undertow to version 1.4.17, 1.3.31, 2.0.0 or later to include the header parsing fix. Verify that any upstream proxies also handle whitespace-normalized headers consistently.

Fix this in Undertow Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing6.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,220
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,552.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2017-12165 in production — separate from our analysis above.

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What this is

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.

What belongs here
  • 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