CVE-2026-89022

BookStack before 26.05.5 contains an authentication bypass vulnerability in its social login implementation that allows unauthenticated attackers to sign in as arbitrary users by authenticating through a different social provider sharing the same driver_id namespace. Attackers can authenticate at one enabled social provider using a user ID that matches an account linked to a different social provider, bypassing credential verification entirely because the SocialAuthService::handleLoginCallback query ignores the driver column when retrieving linked account records.

• https://www.bookstackapp.com/blog/bookstack-release-v26-05-5/
• https://www.vulncheck.com/advisories/bookstack-authentication-bypass-via-social-login-provider-confusion