CVE-2025-12543

CRITICAL
2026-01-07 [email protected] GHSA-j382-5jj3-vw4j
9.6
CVSS 3.1
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CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
Low

Lifecycle Timeline

3
Patch Released
Mar 31, 2026 - 21:13 nvd
Patch available
Analysis Generated
Mar 12, 2026 - 21:54 vuln.today
CVE Published
Jan 07, 2026 - 17:15 nvd
CRITICAL 9.6

Tags

Java Information Disclosure Process Automation Jboss Enterprise Application Platform Expansion Pack Jboss Enterprise Application Platform Undertow Build Of Apache Camel Fuse Data Grid Single Sign On Redhat

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.

Analysis

Undertow HTTP server (used in WildFly, JBoss EAP) fails to validate Host headers, enabling cache poisoning, internal network scanning, and session hijacking. Affects a widely-used Java application server component.

Technical Context

Undertow does not reject requests with malformed or malicious Host headers (CWE-20). This enables: (1) Cache poisoning by injecting different Host values that get cached, (2) Internal network scanning by using Host headers to probe internal services, (3) Session hijacking through Host header-based routing manipulation.

Affected Products

Undertow (used in WildFly, JBoss EAP, and other Java applications)

Remediation

Update Undertow/WildFly/JBoss EAP. Configure reverse proxies to normalize Host headers before forwarding.

Priority Score

48
Low Medium High Critical
KEV: 0
EPSS: +0.1
CVSS: +48
POC: 0

Vendor Status

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CVE-2025-12543 vulnerability details – vuln.today
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