Paper/Archive/CVE-2026-31957

CVE-2026-31957

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

EPSS 0.5%CVSS 10.0

critical.is priorityof 100

CVSS 10.0 (CNA)10.0 / 10 × 3030.0 Not in CISA KEV+300.0 EPSS percentile 44.3.443 × 208.9 No public exploit+100.0 SSVC exploitation: none+100.0

Description · from the CVE record

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

ProductAffectedFixed inSource

himmelblau>= 3.0.0, < 3.1.0–CNA

Scores by source

GitHub_M (CNA)10.0CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refgithub.com/himmelblau-idm/himmelblau/security/advisories/GHSA-q746-m2wv-qh4v