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Maven

CVE-2017-12165

HIGH

CVE-2017-12165 is a high-severity (CVSS 7.5) CWE-444 vulnerability in io.undertow:undertow-core. O3 Security confirms whether CVE-2017-12165 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Undertow Request Smuggling vulnerability

Also known asGHSA-5gg7-5wv8-4gcj
Published
Jul 27, 2018
Updated
Jul 8, 2026
Affected
3 pkgs
Patched
3 / 3
Exploits
None indexed

Blast Radius

3 pkgs affected
io.undertow:undertow-coreio.undertow:undertow-coreio.undertow:undertow-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
Mavenio.undertow:undertow-coreall versions1.3.31
Mavenio.undertow:undertow-core1.4.0&&< 1.4.171.4.17
Mavenio.undertow:undertow-core2.0.0.Alpha1&&< 2.0.0.Beta12.0.0.Beta1

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.undertow:undertow-core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update io.undertow:undertow-core to 1.3.31 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2017-12165 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether CVE-2017-12165 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2017-12165. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

Is CVE-2017-12165 in your dependencies?

O3 detects CVE-2017-12165 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.