EUVD-2026-28509
GHSA-72h4-mxfc-jx37
CVSS VectorNVD
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
5DescriptionNVD
Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall performs host matching in a case-sensitive manner, while HTTP hostnames are case-insensitive. This discrepancy can result in heimdall failing to match a rule for a request host that differs only in letter casing, potentially causing the request to be classified differently than intended. This issue has been patched in version 0.17.14.
AnalysisAI
Heimdall's case-sensitive host matching bypasses access control policies when attackers submit HTTP requests with alternate letter casing in the Host header, exploiting the discrepancy between HTTP spec (case-insensitive hostnames) and Heimdall's implementation. Versions prior to 0.17.14 fail to match rules configured for lowercase hostnames when requests arrive with mixed or uppercase casing, potentially routing to permissive default rules and granting unintended access. …
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RemediationAI
Within 24 hours: Audit current Heimdall deployment version and inventory all configured hostname-based access control rules. Within 7 days: Implement case-insensitive hostname matching validation rules as a compensating control and review default rule enforcement flags to ensure deny-by-default posture is active. …
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External POC / Exploit Code
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