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Vulnerabilities / CVE-2025-12543

critical

CVE-2025-12543

undertow-core: Undertow HTTP Server Fails to Reject Malformed Host Headers Leading to Potential Cache Poisoning and SSRF

Published Modified CWE 20
In the Trivy database since at least 24 Oct 2026, 07:11 UTCWhen it arrived before that build is not recorded.

Severity by source

NVD9.6CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
GHSA9.6CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L
Red Hat9.6CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

Trivy's own label is CRITICAL. Rated critical by NVD, GHSA. Rated lower by Red Hat (high), Ubuntu (high).

Description

A flaw was found in the Undertow HTTP server core, which is used in WildFly, JBoss EAP, and other Java applications. The Undertow library fails to properly validate the Host header in incoming HTTP requests.As a result, requests containing malformed or malicious Host headers are processed without rejection, enabling attackers to poison caches, perform internal network scans, or hijack user sessions.

Affected packages and fixed versions

SourcePackageFixed in
maven::GitHub Security Advisory Mavenio.undertow:undertow-core2.3.21.Final, 2.2.39.Final
chainguardwildfly39.0.0-r0
debian 14undertowno fix listed
ubuntu 16.04-ESMundertow1.3.16-1ubuntu0.1~esm1
ubuntu 18.04-ESMundertow1.4.23-3ubuntu0.1~esm1
ubuntu 20.04-ESMundertow2.0.29-1ubuntu0.1~esm1
ubuntu 22.04undertowno fix listed
ubuntu 24.04undertowno fix listed
ubuntu 26.04undertow2.3.20-1ubuntu1
ubuntu 26.10undertow2.3.20-1ubuntu1
wolfiwildfly39.0.0-r0

References

All 34 references

Vulnerability data compiled from the Trivy vulnerability database (trivy-db, Aqua Security, Apache License 2.0), which aggregates third-party advisories. CVE records are published by The MITRE Corporation under the CVE Terms of Use; CVE is a trademark of MITRE. This product uses data from the NVD API but is not endorsed or certified by the NVD. Severity, titles and advisory data from the GitHub Advisory Database (CC BY 4.0), Red Hat security data (CC BY 4.0) and the other sources linked on each entry. Entries may be summarised or re-formatted; the linked original is the authoritative record.