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.
- Published Sep 15, 2026
- CVSS 9.1 critical
- 0.5% chance of exploitation in the next 30 days (EPSS)
- A fix is available