Improper Neutralization of HTTP Headers for Scripting Syntax in Undertow - CVE-2025-12543
Published: January 10, 2026
Vulnerability identifier: #VU121145
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:L/SA:N/E:U/U:Green
CVE-ID: CVE-2025-12543
CWE-ID: CWE-644
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Red Hat Inc.
Affected software:
Undertow
Undertow
Detailed vulnerability description
The vulnerability allows a remote attacker to perform spoofing attack.
The vulnerability exists due to improper input validation when processing HTTP requests. A remote non-authenticated attacker can send a specially crafted HTTP request with an arbitrary Host header that will be accepted by the application.
Successful exploitation of the vulnerability may allow an attacker to perform cross-site scripting, cache poisoning or session hijacking attacks.
How to mitigate CVE-2025-12543
Install updates from vendor's website.