CVE-2026-42272 HIGH

CVE-2026-42272: Heimdall: Case-sensitive handling of URL-encoded slashes may lead to inconsistent path interpretation

Vendor Dadrus
Product heimdall
Weakness CWE-436
Published May 8, 2026
Last update May 8, 2026

CVSS base score

7.8/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

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

What the vulnerability does

01Description

Heimdall 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.

Key dates

02Disclosure timeline

May 8, 2026 CVE published
May 8, 2026 Record updated