CVE-2026-42272 PUBLISHED

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

Assigner: GitHub_M
Reserved: 26.04.2026 Published: 08.05.2026 Updated: 08.05.2026

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.

Metrics

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
CVSS Score: 7.8

Product Status

Vendor dadrus
Product heimdall
Versions
  • Version < 0.17.14 is affected

References

Problem Types

  • CWE-436: Interpretation Conflict CWE
  • CWE-178: Improper Handling of Case Sensitivity CWE