CVE-2025-12543

critical

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.

References

Details

Source: Mitre, NVD

Published: 2026-01-07

Updated: 2026-01-08

Risk Information

CVSS v2

Base Score: 9.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:P

Severity: High

CVSS v3

Base Score: 9.6

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

Severity: Critical

EPSS

EPSS: 0.00095