Vulnerability · Published Mar 11, 2026 · Assigned by GitHub_M
CVE-2026-31957Himmelblau unset domain configuration can allow any-tenant authentication at first login for remote deployments
Critical 10.0
In plain English
A critical-severity security flaw in himmelblau from himmelblau-idm. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities).
Official description
Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. From 3.0.0 to before 3.1.0, if Himmelblau is deployed without a configured tenant domain in himmelblau.conf, authentication is not tenant-scoped. In this mode, Himmelblau can accept authentication attempts for arbitrary Entra ID domains by dynamically registering providers at runtime. This behavior is intended for initial/local bootstrap scenarios, but it can create risk in remote authentication environments. This vulnerability is fixed in 3.1.0.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| himmelblau-idm | himmelblau | >= 3.0.0, < 3.1.0 |
Weakness: CWE-1188 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H