CVE-2025-12543
Critical · 9.6CVSS
9.6
EPSS
1.3%
Published
Jan 7, 2026
CISA due date
—
The record
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.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Maven | io.undertow:undertow-core | 0 | 2.2.39.Final |
| Maven | io.undertow:undertow-core | 2.3.0.Alpha1 | 2.3.21.Final |
| Maven | io.undertow:undertow-core | 2.4.0.Alpha1 | No fix |
| Chainguard | wildfly-openjdk-17 | 0 | 39.0.0-r0 |
| Chainguard | wildfly-openjdk-21 | 0 | 39.0.0-r0 |
| Wolfi | wildfly-openjdk-17 | 0 | 39.0.0-r0 |
| Wolfi | wildfly-openjdk-21 | 0 | 39.0.0-r0 |
| maven | io.undertow/undertow-core | 2.4.0.Alpha1 | No fix |
Related vulnerabilities
- GHSA-33hj-rcmx-86mv Undertow Servlets Vulnerable to Remote DoS via OutOfMemoryError when Passed Large… Also affects io.undertow:undertow-core
- CVE-2024-4027 A flaw was found in Undertow. Also affects io.undertow:undertow-core
- CVE-2024-3884 A flaw was found in Undertow that can cause remote denial of service attacks. Also affects io.undertow:undertow-core
- CVE-2024-4109 undertow: information leakage via HTTP/2 request header reuse Also affects io.undertow:undertow-core
- CVE-2023-4639 A flaw was found in Undertow, which incorrectly parses cookies with certain… Also affects io.undertow:undertow-core
- CVE-2023-1973 A flaw was found in Undertow package. Also affects io.undertow:undertow-core
- CVE-2024-7885 A vulnerability was found in Undertow where the ProxyProtocolReadListener reuses the same… Also affects io.undertow:undertow-core
- CVE-2024-3653 A vulnerability was found in Undertow. Also affects io.undertow:undertow-core