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Advisory record · GHSA-8v4x-mgvp-p658

Undertow is Vulnerable to HTTP Request/Response Smuggling

CVSS 8.7 HighEPSS 0.0073 · 54th percentile

Published by the GitHub Advisory Database at 27 Mar 2026, 18:31 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
io.undertow:undertow-coreMaven<2.2.40.Final || >=2.3.0.Final, <2.3.25.Final2.2.40.Final, 2.3.25.Final
Identifiers
GHSA-8v4x-mgvp-p658 · CVE-2026-28368
Weakness (CWE)
CWE-444
Tags
Published
27 Mar 2026
Updated
4 Nov 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Undertow (io.undertow:undertow-parent) versions up to and including 2.3.23.Final parse HTTP header names differently from some upstream proxies. A remote attacker can send specially crafted requests that exploit this mismatch to smuggle requests, potentially bypassing security controls and reaching unauthorized resources. The source gives few details on specific conditions. No fixed version is listed.

Written 2 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
8.7 High 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N CNA (redhat)
  • CISA KEV Not listed.
  • EPSS 0.0073, the 54th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 27 Mar 2026, 16:13 UTC Confirmed by the CVE List
  2. 27 Mar 2026, 17:16 UTC Confirmed by NVD
  3. 27 Mar 2026, 18:31 UTC Confirmed by GitHub Advisory Database
  4. 31 Oct 2026, 14:17 UTC First seen by agentprime
  5. 31 Oct 2026, 14:17 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.