CVE-2025-12543
criticalA 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.
9.6
cvss
critical
common vulnerability scoring system v3.1. measures intrinsic severity on a 0-10 scale.
epss
0.0005
kev
no
cisa known exploited vulnerabilities catalog. confirmed active exploitation.
CVSS 3.1
Common Vulnerability Scoring System v3.1
9.6
/ 10
CRITICAL
exploitability
Attack Vector
Network
Attack Vector (AV:N): exploitable remotely over the network — most dangerous. no physical or adjacent access needed.
Attack Complexity
Low
Attack Complexity (AC:L): no special conditions needed. attack can be reliably reproduced.
Privileges Required
None
Privileges Required (PR:N): no authentication needed. any anonymous attacker can exploit this.
User Interaction
Required
User Interaction (UI:R): victim must perform some action (e.g. clicking a link, opening a file).
impact
Scope
Changed
Scope (S:C): exploitation impacts resources beyond the vulnerable component.
Confidentiality
High
Confidentiality (C:H): total information disclosure. attacker gains access to all data within the component.
Integrity
High
Integrity (I:H): complete data modification possible. attacker can modify any data.
Availability
Low
Availability (A:L): reduced performance or partial service interruption.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L
activity density
rdintel assessment
public exploit available. prioritize patching.
detection rules available.
composite score from 15+ signals including exploitation status, epss probability, detection coverage, and community attention. 0-100 scale.
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