CVE-2026-42273: Heimdall: Case-sensitive host matching may lead to policy bypass
Vulnerability summary
CVE-2026-42273 is a high (CVSS 7.8) Improper Handling of Case Sensitivity vulnerability in dadrus heimdall. EPSS estimates a 0.30% chance of exploitation in the next 30 days, higher than 22.9% of scored vulnerabilities.
Severe, CVSS 7.8 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 1 · Related 1Timeline
- 08-05-2026PublishedVulnerability first disclosed.
- 08-05-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
3 scores · 3 sources · 1 version- OSV · GoEcosystem advisory · calculated7.8HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
- NVDNIST7.8HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS trend
Probability
0.30%
Chance of exploitation in the next 30 days
Percentile
23%
Versus all other CVEs
30-day change
Decrease -0.22 pp
From 0.52% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-178Improper Handling of Case SensitivityThe product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.
- CWE-436Interpretation ConflictProduct A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state.
Affected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Dadrus1 product
- heimdall< 0.17.14
Github.com/dadrus1 product
- heimdall< 0.17.14
2 vendors · 2 products
References
6 links
- github.com/dadrus/heimdallPACKAGE