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Undertow HTTP server core doesn't properly validate the Host header in incoming HTTP requests

🗓️ 07 Jan 2026 18:30:25Reported by GitHub Advisory DatabaseType 
github
 github🔗 github.com👁 30 Views

Undertow server fails to validate Host header, enabling cache poisoning, network scans, and session hijacking.

Related
Detection
Refs
ReporterTitlePublishedViews
Family
IBM Security Bulletins		Security Bulletin: IBM Terracotta is affected by two Undertow vulnerabilities that could allow remote denial of service attacks and Host header manipulation leading to cache poisoning or session hijacking
23 Feb 202619:06
–ibm
IBM Security Bulletins		Security Bulletin: IBM InfoSphere Information Server is affected by multiple vulnerabilities in Undertow
24 Mar 202619:29
–ibm
IBM Security Bulletins		Security Bulletin: Improper Host Header Validation in Undertow HTTP Server Enables Cache Poisoning and Session Hijacking affects watsonx.data
9 Apr 202616:52
–ibm
IBM Security Bulletins		Security Bulletin: DevOps Test Performance contains a vulnerability related to use of the Undertow server core
10 Apr 202614:17
–ibm
ATTACKERKB		CVE-2025-12543
7 Jan 202616:04
–attackerkb
Broadcom		Undertow-core: undertow http server fails to reject malformed host headers leading to potential cache poisoning and ssrf (CVE-2025-12543)
26 Jan 202600:00
–broadcom
Chainguard		CVE-2025-12543 vulnerabilities
27 Jan 202601:17
–cgr
Circl		CVE-2025-12543
7 Jan 202616:56
–circl
CNNVD		Red Hat Undertow 安全漏洞
7 Jan 202600:00
–cnnvd
CVE		CVE-2025-12543
7 Jan 202616:04
–cve
Rows per page
Vulners
Node
io.undertowundertow-coreRange<2.2.39.Finalmaven
OR
io.undertowundertow-coreRange2.3.0.Alpha1–2.3.21.Finalmaven
OR
io.undertowundertow-coremaven

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18 Mar 2026 18:31Current
6.6Medium risk
Vulners AI Score6.6
CVSS 3.19.6
EPSS0.00031
SSVC
CWE-20
Undertowhost headercache poisoningnetwork scanssession hijackingweb server
30