TI-2026-30583 Aliases CVE-2026-42272 GHSA-43jv-5j4x-qv67

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

MEDIUM 42CWE-178Published 2026-05-08 · Updated 2026-05-08

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: —
Confidentiality · integrity · availability: None · None · None
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00396 34th percentileScored 2026-11-07

Fix Fixed heimdall (dadrus): 0.17.14github.com/dadrus/heimdall (Go): 0.17.14

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
dadrus	heimdall	before 0.17.14	0.17.14	Patch available	CNA
—	github.com/dadrus/heimdall (Go)	before 0.17.14	0.17.14	Patch available	GHSA-43jv-5j4x-qv67

heimdall Vendordadrus Affected before 0.17.14 Fixed in 0.17.14 Patch available CNA
github.com/dadrus/heimdall (Go) Vendor— Affected before 0.17.14 Fixed in 0.17.14 Patch available GHSA-43jv-5j4x-qv67

Remediation

Fix · CNA heimdall (dadrus) Fixed in 0.17.14
Fix · GHSA-43jv-5j4x-qv67 github.com/dadrus/heimdall (Go) Fixed in 0.17.14 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-42272
2026-10-03 Alias added: GHSA-43jv-5j4x-qv67

References

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-42272

Other 5

TI-2026-25280 Heimdall: Path received via Envoy gRPC corrupted when containing query string CVSS 3.1HIGH 8.2
TI-2026-79758 Forwarded header injection in Heimdall proxy mode via Host header CVSS 4.0HIGH 7.0
TI-2026-30585 Heimdall: Authorization bypass via path normalization mismatch CVSS 4.0HIGH 7.8
TI-2026-30584 Heimdall: Case-sensitive host matching may lead to policy bypass CVSS 4.0HIGH 7.8
TI-2026-79759 IP spoofing in Heimdall via unvalidated forwarding headers CVSS 4.0HIGH 7.0

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences