Heimdall: Case-sensitive handling of URL-encoded slashes may lead to inconsistent path interpretation

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Summary

CVECVE-2026-42272
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-08 04:16:22 UTC
Updated2026-05-08 04:16:22 UTC
DescriptionHeimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall handles URL-encoded slashes (%2F) in a case-sensitive manner, while percent-encoding is defined to be case-insensitive. As a result, the lowercase equivalent (%2f) is not recognized and therefore not processed as expected when allow_encoded_slashes is set to off (the default setting). This discrepancy can lead to differences in how request paths are interpreted by heimdall and upstream components, which may result in authorization bypass. This issue has been patched in version 0.17.14.

Risk And Classification

Primary CVSS: v4.0 7.8 HIGH from [email protected]

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

Problem Types: CWE-178 | CWE-436 | CWE-436 CWE-436: Interpretation Conflict | CWE-178 CWE-178: Improper Handling of Case Sensitivity

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary7.8HIGHCVSS: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/C...
4.0CNADECLARED7.8HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
None
Availability
None
Sub Conf.
High
Sub Integrity
High
Sub Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Dadrus Heimdall affected < 0.17.14 Not specified

References

ReferenceSourceLinkTags
github.com/dadrus/heimdall/releases/tag/v0.17.14 [email protected] github.com
github.com/dadrus/heimdall/commit/8b0de6aba23a047cfee3081df878271bb17f4351 [email protected] github.com
github.com/dadrus/heimdall/security/advisories/GHSA-43jv-5j4x-qv67 [email protected] github.com
github.com/dadrus/heimdall/pull/3207 [email protected] github.com
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