Host header injection in Undertow

1) Improper Neutralization of HTTP Headers for Scripting Syntax

EUVDB-ID: #VU121145

Risk: Medium

CVSSv4.0: 2.7 [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 - Improper Neutralization of HTTP Headers for Scripting Syntax

Exploit availability: No

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.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Undertow: All versions

CPE2.3

• cpe:2.3:a:red_hat:undertow:*:*:*:*:*:wildfly_core:*:*

External links

https://bugzilla.redhat.com/show_bug.cgi?id=2408784

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.