Loading...
Skip to main content
GeekWala

CVE-2025-12543 — Vulnerability in io.undertow:undertow-core — CVE...

CRITICAL

Undertow HTTP server core doesn't properly validate the Host header in incoming HTTP requests

Published January 7, 2026Updated September 10, 2026Source: osv

Summary

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.

Advisory Timeline

  • First published January 7, 2026 (278 days ago).
  • Last revised September 10, 2026 — 245 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

Maven
Update io.undertow:undertow-core to 2.2.39.Final or later
<!-- Update pom.xml dependency version to 2.2.39.Final for io.undertow:undertow-core -->
Maven
Update io.undertow:undertow-core to 2.3.21.Final or later
<!-- Update pom.xml dependency version to 2.3.21.Final for io.undertow:undertow-core -->

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (3)

Affects 1 ecosystem: maven (1).

PackageEcosystemAffectedFixed In
io.undertow:undertow-core
maven
2.4.0.Alpha1No fix available
io.undertow:undertow-core
maven
1.0.0.Alpha1, 1.0.0.Alpha10, 1.0.0.Alpha11, 1.0.0.Alpha12 (+303 more)2.2.39.Final
io.undertow:undertow-core
maven
2.3.0.Alpha1, 2.3.0.Alpha2, 2.3.0.Beta1, 2.3.0.Final (+20 more)2.3.21.Final

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

  • CWE-20
    Improper Input ValidationMITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 9.6 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
Low

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

References

Frequently Asked Questions

What is CVE-2025-12543?
Undertow HTTP server core doesn't properly validate the Host header in incoming HTTP requests This vulnerability has been assigned a severity rating of CRITICAL (CVSS score: 9.6/10).
How do I check if my project is affected by CVE-2025-12543?
CVE-2025-12543 affects io.undertow:undertow-core. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2025-12543 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
9.6

Exploitation is straightforward and causes maximum impact. Patch immediately.

Also Known As

GHSA-j382-5jj3-vw4j

Related CVEs

More Maven advisories

Check if you're affected

Scan your dependencies to see if this vulnerability affects your projects.

Scan Your Dependencies