CVE-2026-42273: CWE-436: Interpretation Conflict in dadrus heimdall
CVE-2026-42273 is a high-severity vulnerability in dadrus heimdall, a cloud native Identity Aware Proxy and Access Control Decision service. The issue arises because heimdall versions prior to 0.17.14 perform host matching in a case-sensitive manner, whereas HTTP hostnames are case-insensitive by standard. This mismatch can cause heimdall to fail to match rules correctly when the request host differs only in letter casing, potentially leading to unintended request classification. The vulnerability has been addressed in version 0.17.14.
AI Analysis
Technical Summary
Heimdall before version 0.17.14 performs host matching in a case-sensitive way, conflicting with the HTTP standard that hostnames are case-insensitive. This interpretation conflict (CWE-436) can cause requests to be misclassified if the hostname casing differs, potentially affecting access control decisions. The issue is fixed in version 0.17.14. The CVSS 4.0 score is 7.8 (high severity), indicating network attack vector, low attack complexity, no privileges or user interaction required, but with high scope and impact on confidentiality, integrity, and availability.
Potential Impact
Requests with hostnames differing only by letter case may bypass or be incorrectly matched by access control rules, potentially allowing unauthorized access or denial of legitimate access. This could lead to unintended exposure or blocking of resources protected by heimdall. There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrade heimdall to version 0.17.14 or later, where the host matching logic has been corrected to be case-insensitive in accordance with HTTP standards. Patch status is confirmed by the vendor's versioning information. No additional mitigations are specified.
CVE-2026-42273: CWE-436: Interpretation Conflict in dadrus heimdall
Description
CVE-2026-42273 is a high-severity vulnerability in dadrus heimdall, a cloud native Identity Aware Proxy and Access Control Decision service. The issue arises because heimdall versions prior to 0.17.14 perform host matching in a case-sensitive manner, whereas HTTP hostnames are case-insensitive by standard. This mismatch can cause heimdall to fail to match rules correctly when the request host differs only in letter casing, potentially leading to unintended request classification. The vulnerability has been addressed in version 0.17.14.
CVSS v4.0
Score 7.8high
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Heimdall before version 0.17.14 performs host matching in a case-sensitive way, conflicting with the HTTP standard that hostnames are case-insensitive. This interpretation conflict (CWE-436) can cause requests to be misclassified if the hostname casing differs, potentially affecting access control decisions. The issue is fixed in version 0.17.14. The CVSS 4.0 score is 7.8 (high severity), indicating network attack vector, low attack complexity, no privileges or user interaction required, but with high scope and impact on confidentiality, integrity, and availability.
Potential Impact
Requests with hostnames differing only by letter case may bypass or be incorrectly matched by access control rules, potentially allowing unauthorized access or denial of legitimate access. This could lead to unintended exposure or blocking of resources protected by heimdall. There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrade heimdall to version 0.17.14 or later, where the host matching logic has been corrected to be case-insensitive in accordance with HTTP standards. Patch status is confirmed by the vendor's versioning information. No additional mitigations are specified.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-26T11:53:27.707Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69fd5dbdcbff5d86108b646d
Added to database: 05/08/2026, 03:51:25 UTC
Last enriched: 05/15/2026, 11:03:41 UTC
Last updated: 07/31/2026, 19:22:58 UTC
Views: 85
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