Vulnerability · Published May 8, 2026 · Assigned by GitHub_M
CVE-2026-42273Heimdall: Case-sensitive host matching may lead to policy bypass
High 7.8
In plain English
A high-severity security flaw in heimdall from dadrus. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall performs host matching in a case-sensitive manner, while HTTP hostnames are case-insensitive. This discrepancy can result in heimdall failing to match a rule for a request host that differs only in letter casing, potentially causing the request to be classified differently than intended. This issue has been patched in version 0.17.14.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/dadrus/heimdall | 0.17.14 | GHSA-72h4-mxfc-jx37 |
| Go | github.com/dadrus/heimdall | 0.17.14 | GO-2026-5200 |
Affected products (as reported)
Weakness: CWE-436, CWE-178 · 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
References
- https://github.com/dadrus/heimdall/security/advisories/GHSA-72h4-mxfc-jx37 x_refsource_CONFIRM
- https://github.com/dadrus/heimdall/pull/3208 x_refsource_MISC
- https://github.com/dadrus/heimdall/commit/3d05e56a9e7ef0355f17482b4322054af4e85943 x_refsource_MISC
- https://github.com/dadrus/heimdall/releases/tag/v0.17.14 x_refsource_MISC