Threat Intelligence Database

CVE-2026-102631 is an improper authentication vulnerability in Canonical's authd before version 0.7.1. The issue arises from how user identity matching is performed during login, where fallback to username matching can cause account reassignment if an identity provider reassigns an email address. This allows a new user to inherit the previous user's local UID and home directory, gaining unauthorized access to files and credentials such as SSH keys and cloud API tokens. Administrators are advised to lock or delete local authd accounts corresponding to removed identity provider accounts to mitigate this risk.

authd prior to version 0.6.4 contains a logic error in primary group ID assignment that can lead to local privilege escalation. When a user's primary group ID (GID) differs from their UID, either because the account was created with authd prior to version 0.5.4 or because the primary group was manually changed via the `authctl group set-gid` command, and the user's identity provider record is updated, authd incorrectly resets the user's primary group ID to their UID upon next login. This causes newly created files and directories to be owned by the wrong group, causing denial of service issues, and potentially granting unintended access to other local users and allowing local privilege escalation.

A flaw was found in the temporary user record that authd uses in the pre-auth NSS. As a result, a user login for the first time will be considered to be part of the root group in the context of that SSH session.

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