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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: Mar 5, 2026 Sources: CVE List NVD GHSA BDUCWE-20
NVD MITRE
9.6CVSSCRITICAL
EPSS Score
1.2%
Top 36.4%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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 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
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Weaknesses

CWE-20

Affected Products

undertowRed Hat Inc.
On-prem
Operating Systems / linux-distro
JBoss Enterprise Application PlatformRed Hat Inc.
On-premWeb App
Enterprise Software / itsm-monitoring
Red Hat build of Apache Camel 4.14.4 for Spring Boot 3.5.11Red Hat
On-prem
Operating Systems / linux-distro
Red Hat JBoss Enterprise Application PlatformRed Hat
On-prem
Operating Systems / linux-distro
Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7Red Hat
On-prem
Operating Systems / linux-distro
red hat inc.commercialUSOperating Systemsaka red hat
red hatcommercialUSOperating Systemsaka red hat
and 19 more affected products View all →

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available
Workaround Available

MITRE ATT&CK

1 technique
Initial Access
View detailed technique mapping

References

https://bugzilla.redhat.com/show_bug.cgi?id=2408784
bugzilla.redhat.com
https://access.redhat.com/errata/RHSA-2026:0383
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:0384
access.redhat.com
and 17 more references View all →

Timeline

Published
Jan 7, 2026
Last Updated
Mar 5, 2026

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