What’s Vulnerable › Vulnerabilities

CVE-2026-89022: BookStack < 26.05.5 Authentication Bypass via Social Login Provider Confusion

• Severity: high (CVSS 7.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-15 · updated 2026-09-16
• Weakness: CWE-290

Description

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.

Affected products

• bookstackapp/bookstack: before 26.05.5 — fixed in 26.05.5

How to fix

Upgrade to a fixed version: bookstackapp/bookstack 26.05.5. Check the vendor advisory for mitigations.

References

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

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