CVE-2026-45108 Himmelblau: Authentication Bypass via Cross-User Local Session Impersonation in Device Authorization Grant (DAG) Flow
An attacker can impersonate another user to gain a local Unix session by exploiting a username validation flaw in the Device Authorization Grant flow.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-45108?
CVE-2026-45108 is a high-severity authentication bypass vulnerability in himmelblau-idm himmelblau, published on 27 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-863
Which versions are affected by CVE-2026-45108?
Linux distribution packages (3)
himmelblau SUSE:Linux Enterprise Server 16.0 | All versions | 2.3.11+git1.116c6763-160000.1.1 |
himmelblau SUSE:Linux Enterprise Server for SAP applications 16.0 | All versions | 2.3.11+git1.116c6763-160000.1.1 |
himmelblau openSUSE:Leap 16.0 | All versions | 2.3.11+git1.116c6763-160000.1.1 |
How do I fix CVE-2026-45108?
Upgrade to a fixed version.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-45108 being exploited?
There is no known exploitation of CVE-2026-45108 in the wild and no public exploit code.
Sources
Also known as GHSA-pmxh-j4r6-88mv, SUSE-SU-2026:22186-1, openSUSE-SU-2026:21111-1.