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undertow-core: Undertow HTTP Server Fails to Reject Malformed Host Headers Leading to Potential Cache Poisoning and SSRF

🗓️ 06 Oct 2026 11:40:46Reported by RedHatType 
redhat
 redhat🔗 access.redhat.com👁 6 Views

Malformed Host headers in Undertow core allow cache poisoning and SSRF.

Related
Packages
Refs
ReporterTitlePublishedViews
Family
ibm
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
IBM Security Bulletins		Security Bulletin: IBM InfoSphere Information Server is affected by multiple vulnerabilities in Undertow
24 Mar 202619:29
–ibm
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
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
attackerkb		CVE-2025-12543
7 Jan 202616:04
–attackerkb
bdu_fstec
BDU FSTEC		The vulnerability of the Undertow HTTP server’s kernel allows for attacks using SSRF, due to errors in the mechanism for processing input data when handling Host headers.
9 Jan 202600:00
–bdu_fstec
broadcom
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
cgr
Chainguard		CVE-2025-12543 vulnerabilities
27 Jan 202601:17
–cgr
circl
Circl		CVE-2025-12543
7 Jan 202616:56
–circl
cnnvd
CNNVD		Red Hat Undertow 安全漏洞
7 Jan 202600:00
–cnnvd
Rows per page
OSOS VersionArchitecturePackagePackage VersionFilename
Red Hat Enterprise Linux8noarchrh-sso7-keycloak18.0.20-1.redhat_00001.1.el8ssorh-sso7-keycloak-18.0.20-1.redhat_00001.1.el8sso.noarch.rpm
Red Hat Enterprise Linux8noarchrh-sso7-keycloak-server18.0.20-1.redhat_00001.1.el8ssorh-sso7-keycloak-server-18.0.20-1.redhat_00001.1.el8sso.noarch.rpm

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09 Oct 2026 03:47Current
7.4High risk
Vulners AI Score7.4
CVSS 3.19.6
EPSS0.01333
SSVC
CWE-20
UndertowHost headercache poisoningSSRF
6