team-alembic/ash_authentication

Authentication Bypass by Spoofing vulnerability in team-alembic AshAuthentication allows account takeover of local users via OAuth2/OIDC sign-in. AshAuthentication's OAuth2 and OIDC family strategies matched the local user by email address (an upsert on the email field, or a user-defined sign-in filter) rather than by the OpenID Connect iss/sub claim combination. Per OpenID Connect Core §5.7, only iss/sub uniquely and stably identifies an end-user; other claims, including email, MUST NOT be used as unique identifiers. A provider login presenting a victim's email, including an unverified email, a reused email, or an account with email_verified: false, resolved to and signed in as the victim's existing local account. An unauthenticated attacker who can register an account on any accepted OAuth provider with the victim's email (or who benefits from provider-side email reuse or reclamation) obtains the victim's full local privileges. The fix resolves users by the (strategy, sub) identity stored in a user identity resource, and only links a new sub to an existing local account by email when the provider's email_verified claim is trusted (trust_email_verified?). This issue affects ash_authentication from 0.1.0 before 4.14.0 and from 5.0.0-rc.0 before 5.0.0-rc.10.

Ash Authentication provides authentication for the Ash framework. The confirmation flow for account creation currently uses a GET request triggered by clicking a link sent via email. Some email clients and security tools (e.g., Outlook, virus scanners, and email previewers) may automatically follow these links, unintentionally confirming the account. This allows an attacker to register an account using another user’s email and potentially have it auto-confirmed by the victim’s email client. This does not allow attackers to take over or access existing accounts or private data. It is limited to account confirmation of new accounts only. This vulnerability is fixed in 4.7.0.