CVE-2026-67328: Better-Auth SSO

High severity, CVSS 8.1. EPSS: 0.5% chance of exploitation in the next 30 days.

@better-auth/sso versions before 1.6.21 contain multiple authentication bypass vulnerabilities in SSO provider handling that allow attackers to sign in as arbitrary users. Attackers can exploit domain verification parsing mismatches, orphaned provider accounts, unbound SAML assertions, or reflected XSS on logout endpoints to gain unauthorized session access and account takeover.

Affected products

• Better-Auth SSO: before 1.6.21 (fixed in 1.6.21); from 1.7.0-beta.0, before 1.7.0-beta.10 (fixed in 1.7.0-beta.10)

Published 2026-08-01. Last modified 2026-10-08.