CVE-2026-42273CWE-178CWE-436

Heimdall: Case-sensitive host matching may lead to policy bypass

High · published May 8, 2026

CVSS v4.0
7.8
EPSS
1%
Percentile
43.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
7.8 · HIGH
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
EPSS
0.00524 · 43.6th percentile
Weaknesses
CWE-178 · Improper Handling of Case Sensitivity; CWE-436 · Interpretation Conflict
Published
2026-05-08T03:42Z
EPSS history
Timeline
  • 08 MAY 03:42Z
    Heimdall: Case-sensitive host matching may lead to policy bypass
    cvelistv5