Himmelblau versions from 2.0.0 up to but not including 2.3.11, and from 3.0.0-alpha up to but not including 3.1.5, contain an authentication bypass vulnerability in the Device Authorization Grant flow. This flaw allows a user within the same Microsoft Azure Entra ID domain to gain a local Unix session as another user by using their own valid credentials.
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.
Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. Prior to 3.1.0 and 2.3.8, the himmelblaud-tasks daemon, running as root, writes Kerberos cache files under /tmp/krb5cc_<uid> without symlink protections. Since commit 87a51ee, PrivateTmp is explicitly removed from the tasks daemon's systemd hardening, exposing it to the host /tmp. A local user can exploit this via symlink attacks to chown or overwrite arbitrary files, achieving local privilege escalation. This vulnerability is fixed in 3.1.0 and 2.3.8.
CVE-2026-31957 is a critical vulnerability in himmelblau versions 3.0.0 up to but not including 3.1.0, an interoperability suite for Microsoft Azure Entra ID and Intune. The issue arises when himmelblau is deployed without a configured tenant domain in its configuration file, causing authentication to be unscoped to any tenant. This allows the system to accept authentication attempts for arbitrary Entra ID domains by dynamically registering providers at runtime, which is intended only for initial or local bootstrap scenarios. In remote authentication environments, this behavior can lead to unauthorized access, compromising confidentiality, integrity, and availability. The vulnerability has a CVSS score of 10.0, indicating critical severity, and is fixed in version 3.
Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. Himmelblau 0.9.x derives numeric GIDs for Entra ID groups from the group display name when himmelblau.conf `id_attr_map = name` (the default configuration). Because Microsoft Entra ID allows multiple groups with the same `displayName` (including end-user–created personal/O365 groups, depending on tenant policy), distinct directory groups can collapse to the same numeric GID on Linux. This issue only applies to Himmelblau versions 0.9.0 through 0.9.22. Any resource or service on a Himmelblau-joined host that enforces authorization by numeric GID (files/dirs, etc.) can be unintentionally accessible to a user who creates or joins a different Entra/O365 group that happens to share the same `displayName` as a privileged security group. Users should upgrade to 0.9.23, or 1.0.0 or later, to receive a patch. Group to GID mapping now uses Entra ID object IDs (GUIDs) and does not collide on same-name groups. As a workaround, use tenant policy hardening to restrict arbitrary group creation until all hosts are patched.
Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. In versions 0.8.0 through 0.9.21 and 1.0.0-beta through 1.1.0, Himmelblau stores the cloud TGT received during logon in the Kerberos credential cache. The created credential cache collection and received credentials are stored as world readable. This is fixed in versions 0.9.22 and 1.2.0. To work around this issue, remove all read access to Himmelblau caches for all users except for owners.
Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. When debugging is enabled for Himmelblau in version 1.0.0, the himmelblaud_tasks service leaks an Intune service access token to the system journal. This short-lived token can be used to detect the host's Intune compliance status, and may permit additional administrative operations for the Intune host device (though the API for these operations is undocumented). This is fixed in version 1.1.0. To workaround this issue, ensure that Himmelblau debugging is disabled.
Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. A vulnerability present in versions 0.9.10 through 0.9.16 allows a user to authenticate to a Linux host via Himmelblau using an *invalid* Linux Hello PIN, provided the host is offline. While the user gains access to the local system, Single Sign-On (SSO) fails due to the network being down and the inability to issue tokens (due to a failure to unlock the Hello key). The core issue lies in an incorrect assumption within the `acquire_token_by_hello_for_business_key` function: it was expected to return a `TPMFail` error for an invalid Hello key when offline, but instead, a preceding nonce request resulted in a `RequestFailed` error, leading the system to erroneously transition to an offline success state without validating the Hello key unlock. This impacts systems using Himmelblau for authentication when operating in an offline state with Hello PIN authentication enabled. Rocky Linux 8 (and variants) are not affected by this vulnerability. The problem is resolved in Himmelblau version 0.9.17. A workaround is available for users who cannot immediately upgrade. Disabling Hello PIN authentication by setting `enable_hello = false` in `/etc/himmelblau/himmelblau.conf` will mitigate the vulnerability.
Himmelblau is an interoperability suite for Microsoft Azure Entra ID and Intune. Himmelblau versions 0.9.0 through 0.9.14 and 1.00-alpha are vulnerable to a privilege escalation issue when Entra ID group-based access restrictions are configured using group display names instead of object IDs. Starting in version 0.9.0, Himmelblau introduced support for specifying group names in the `pam_allow_groups` configuration option. However, Microsoft Entra ID permits the creation of multiple groups with the same `displayName` via the Microsoft Graph API—even by non-admin users, depending on tenant settings. As a result, a user could create a personal group with the same name as a legitimate access group (e.g., `"Allow-Linux-Login"`), add themselves to it, and be granted authentication or `sudo` rights by Himmelblau. Because affected Himmelblau versions compare group names by either `displayName` or by the immutable `objectId`, this allows bypassing access control mechanisms intended to restrict login to members of official, centrally-managed groups. This issue is fixed in Himmelblau version **0.9.15** and later. In these versions, group name matching in `pam_allow_groups` has been deprecated and removed, and only group `objectId`s (GUIDs) may be specified for secure group-based filtering. To mitigate the issue without upgrading, replace all entries in `pam_allow_groups` with the objectId of the target Entra ID group(s) and/or audit your tenant for groups with duplicate display names using the Microsoft Graph API.