What’s Vulnerable › Vulnerabilities
CVE-2026-31957: Himmelblau unset domain configuration can allow any-tenant authentication at first login for remote deployments
- Severity: critical (CVSS 10.0 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.5% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-03-11 · updated 2026-06-17
- Weakness: CWE-1188
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
- himmelblau-idm himmelblau: before 3.1.0 — fixed in 3.1.0
How to fix
Upgrade to a fixed version: himmelblau-idm himmelblau 3.1.0. Check the vendor advisory for mitigations.
References
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