CVE-2026-31957

Himmelblau unset domain configuration can allow any-tenant authentication at first login for remote deployments

State: Published
Severity: 10.0 Critical
Published: Mar 11, 2026
Updated: Mar 12, 2026
Reserved: Mar 10, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	10.0 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H	GitHub_M

Weaknesses

CWE-1188 Insecure Default Initialization of Resource

Affected Products

Product	Versions
himmelblauhimmelblau-idm	>= 3.0.0, < 3.1.0Affected

References

https://github.com/himmelblau-idm/himmelblau/security/advisories/GHSA-q746-m2wv-qh4v

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