CVE-2025-12543
CRITICAL severity · CVSS 9.6 · Improper input validation
9.6CVSS CRITICAL
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.
Impact & exploitability
Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionRequired
Confidentiality impactHigh
Integrity impactHigh
Availability impactLow
Exploit probability (EPSS)1%
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L
Affected products we track (1)
Recommendation
Apply the vendor fix promptly. Open any affected product above for its exact safe version.
Additional information
- NVD record
- https://access.redhat.com/errata/RHSA-2026:0383Advisory
- https://access.redhat.com/errata/RHSA-2026:0384Advisory
- https://access.redhat.com/errata/RHSA-2026:0386Advisory
- https://access.redhat.com/errata/RHSA-2026:3889Advisory
- https://access.redhat.com/errata/RHSA-2026:3890Advisory
- https://access.redhat.com/errata/RHSA-2026:3891Advisory
- https://access.redhat.com/errata/RHSA-2026:3892Advisory
- https://access.redhat.com/errata/RHSA-2026:4915