CVE-2025-12543
Severity
9.6CRITICAL
EPSS
0.0%
top 85.30%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
Timeline
PublishedJan 7
Latest updateApr 2
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:LExploitability: 2.8 | Impact: 6.0
Affected Packages8 packages
🔴Vulnerability Details
4GHSA▶
Undertow HTTP server core doesn't properly validate the Host header in incoming HTTP requests↗2026-01-07
CVEList▶
Undertow-core: undertow http server fails to reject malformed host headers leading to potential cache poisoning and ssrf↗2026-01-07
OSV▶
Undertow HTTP server core doesn't properly validate the Host header in incoming HTTP requests↗2026-01-07
OSV▶
CVE-2025-12543: A flaw was found in the Undertow HTTP server core, which is used in WildFly, JBoss EAP, and other Java applications↗2026-01-07