CVE-2026-110863

CVSS 8.6 (high) · published 2026-10-14

Better Auth @better-auth/sso from 1.7.0-rc.2 before 1.7.3 contains an authentication bypass vulnerability that allows authenticated users to sign in as other users by registering a personal SSO provider. Attackers can copy a legitimate provider's OIDC issuer or SAML entity ID and assert a victim's subject or NameID, because account lookup ignores providerId, creating sessions for victim accounts.

Weakness: CWE-287

Source: NVD CVE-2026-110863

References

• https://github.com/better-auth/better-auth/security/advisories/GHSA-mx9r-x6ww-qjw9
• https://www.vulncheck.com/advisories/better-auth-better-auth-sso-before-1.7.3-authentication-bypass-via-personal-sso-providers

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