What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.8 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-08 · updated 2026-10-26
• Weakness: CWE-178

Description

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.

Affected products

• dadrus heimdall: before 0.17.14

References

• https://github.com/dadrus/heimdall/commit/8b0de6aba23a047cfee3081df878271bb17f4351
• https://github.com/dadrus/heimdall/pull/3207
• https://github.com/dadrus/heimdall/releases/tag/v0.17.14
• https://github.com/dadrus/heimdall/security/advisories/GHSA-43jv-5j4x-qv67

Get alerted when CVE-2026-42272 or the next vulnerability affects your stack