Threat database

CVE-2026-102631 is an improper authentication vulnerability in Canonical's authd before version 0.7.1. The flaw occurs because authd resolves user identity by broker-scoped provider ID but falls back to username matching without rejecting conflicting non-empty provider IDs. This can cause a new user to inherit the previous user's local UID and home directory if an identity provider reassigns an email address. Consequently, the new user can access and modify files, including sensitive credentials like SSH keys and cloud API tokens, belonging to the previous user. Administrators are advised to lock or delete the previous user's local authd account when the corresponding identity provider account is removed.

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.