CVE-2026-34397: himmelblau: NSS fake-primary group lookup reintroduces name collision risk

Severity: high (CVSS 7.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-01 · updated 2026-06-17
Weakness: CWE-269

Description

Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. From versions 2.0.0-alpha to before 2.3.9 and 3.0.0-alpha to before 3.1.1, there is a conditional local privilege escalation vulnerability in an edge-case naming collision. Only authenticated himmelblau users whose mapped CN/short name exactly matches a privileged local group name (e.g., "sudo", "wheel", "docker", "adm") can cause the NSS module to resolve that group name to their fake primary group. If the system uses NSS results for group-based authorization decisions (sudo, polkit, etc.), this can grant the attacker the privileges of that group. This issue has been patched in versions 2.3.9 and 3.1.1.

Affected products

himmelblau-idm himmelblau: from 2.0.0 before 2.3.9; from 3.0.0 before 3.1.1 — fixed in 2.3.9, 3.1.1

How to fix

Upgrade to a fixed version: himmelblau-idm himmelblau 2.3.9, 3.1.1. Check the vendor advisory for mitigations.

References

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