CVE Tools
Sign in

CVE-2025-12543

Undertow-core: undertow http server fails to reject malformed host headers leading to potential cache poisoning and ssrf

Published: Jan 7, 2026Updated: Aug 7, 2026 Sources: CVE List NVD GHSA BDUCWE-20
9.6CRITICAL
NVD MITRE
EPSS Score
1.2%
Top 34.8%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:CC:HI:HA:L
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:CScope
Changed
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:LAvailability
Low
Open in CVSS calculator →

Weaknesses

CWE-20

Affected Products

Red Hat Inc.
commercial·USaka redhat, Red Hat
build of apache camelOn-prem
Operating Systems / linux-distro
data gridOn-prem
Operating Systems / linux-distro
fuseOn-prem
Operating Systems / linux-distro
JBoss Enterprise Application PlatformOn-prem
Operating Systems / linux-distro
jboss enterprise application platform expansion packOn-prem
Operating Systems / linux-distro
process automationOn-prem
Operating Systems / linux-distro
single sign-onOn-prem
Operating Systems / linux-distro
undertowOn-prem
Operating Systems / linux-distro
Maven
package-ecosystem
io.undertow:undertow-core
OSS Libraries
and 24 more affected products View all →

Exploitability

Official Patch Available
Workaround Available
Is your org exposed to CVE-2025-12543?We can run the check for you — a free external exposure review, no install. Check my exposure

Attack Graph

Products CVE Techniques Tactics

Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.

MITRE ATT&CK

1 technique
Initial Access
View detailed technique mapping

References

https://access.redhat.com/errata/RHSA-2026:0383
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:0384
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:0386
access.redhat.com
and 20 more references View all →

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2025-12543 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
Plain-language analysis
Impact assessment and exploitation scenario in plain English
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows