---
cve: "CVE-2025-12543"
severity: "CRITICAL"
cvss: 9.6
epss: "1.2%"
vendor: "Red Hat"
kev: false
exploited: false
published: "2026-01-07 17:15:55"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-03T06:40:57+02:00"
---

# CVE-2025-12543

> 9.6 CRITICAL

## Beschreibung

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-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Erforderlich | good |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Gering | warn |

## Patch verfügbar (OSV)

- 44e259c325f90432313bf107c0c358a24be805b0 (Commit)
- 791c90859980f808e3ce1e258bff78990df7ca95 (Commit)

## Referenzen

- <https://access.redhat.com/errata/RHSA-2026:0383>
- <https://access.redhat.com/errata/RHSA-2026:0384>
- <https://access.redhat.com/errata/RHSA-2026:0386>
- <https://access.redhat.com/errata/RHSA-2026:33371>
- <https://access.redhat.com/errata/RHSA-2026:33372>
- <https://access.redhat.com/errata/RHSA-2026:3889>
- <https://access.redhat.com/errata/RHSA-2026:3890>
- <https://access.redhat.com/errata/RHSA-2026:3891>
- <https://access.redhat.com/errata/RHSA-2026:3892>
- <https://access.redhat.com/errata/RHSA-2026:4915>
- <https://access.redhat.com/errata/RHSA-2026:4916>
- <https://access.redhat.com/errata/RHSA-2026:4917>
- <https://access.redhat.com/errata/RHSA-2026:4924>
- <https://access.redhat.com/security/cve/CVE-2025-12543>
- <https://bugzilla.redhat.com/show_bug.cgi?id=2408784>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2025-12543) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_