CVE-2026-45108

Himmelblau: Authentication Bypass via Cross-User Local Session Impersonation in Device Authorization Grant (DAG) Flow

Published May 27, 2026 CVSS 3.1 · 8.4 High EPSS < 1% KEV · Not listed
Description
Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. From 2.0.0 to before 3.1.5 and 2.3.11, Himmelblau contained an authentication bypass vulnerability in the Device Authorization Grant (DAG) flow that allowed a user within the same Entra ID domain to obtain a local Unix session as another user by providing their own valid credentials. The vulnerability existed in the token_validate function, which validated domain aliases for legitimate multi-domain scenarios but failed to verify that the local part (username) of the authenticated user's UPN matched the requested account username. The function only compared domains, not the complete usernames. This vulnerability is fixed in 3.1.5 and 2.3.11.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Himmelblau-idm
Himmelblau-idm himmelblau
Vendors & Products Himmelblau-idm
Himmelblau-idm himmelblau
Type Values Removed Values Added
Description Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. From 2.0.0 to before 3.1.5 and 2.3.11, Himmelblau contained an authentication bypass vulnerability in the Device Authorization Grant (DAG) flow that allowed a user within the same Entra ID domain to obtain a local Unix session as another user by providing their own valid credentials. The vulnerability existed in the token_validate function, which validated domain aliases for legitimate multi-domain scenarios but failed to verify that the local part (username) of the authenticated user's UPN matched the requested account username. The function only compared domains, not the complete usernames. This vulnerability is fixed in 3.1.5 and 2.3.11.
Title Himmelblau: Authentication Bypass via Cross-User Local Session Impersonation in Device Authorization Grant (DAG) Flow
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 8.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
May 28, 2026, 1:54 PM
Reserved
May 8, 2026, 7:27 PM
Status
Deferred
Published
May 27, 2026, 8:16 PM
Modified
Oct 26, 2026, 11:10 AM