CVE-2025-12543

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.

This vulnerability has an Important severity because it can be remotely exploited without authentication. However, limited user interaction is required for full impact. It could allow attackers to hijack additional accounts, steal credentials, or gain access to internal systems. The issue stems from improper input validation of HTTP Host headers, leading to serious breaches in confidentiality and integrity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use, applicability, or stability.