CVE-2026-67328
Received Received - Intake

Authentication Bypass in Better Auth SSO Provider

Publication date: 2026-08-01

Last updated on: 2026-08-01

Assigner: VulnCheck

Description
@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.

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Meta Information

Published
2026-08-01
Last Modified
2026-08-01
Generated
2026-08-01
AI Q&A
2026-08-01
EPSS Evaluated
N/A
NVD
CVE-2026-67328
EUVD
EUVD-2026-51839

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
better-auth sso to 1.6.21 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

This vulnerability affects @better-auth/sso versions before 1.6.21. It involves multiple authentication bypass flaws in SSO provider handling that let attackers sign in as any user. Exploits include domain verification parsing mismatches, orphaned provider accounts, unbound SAML assertions, or reflected XSS on logout endpoints to gain unauthorized access and take over accounts.

Impact Analysis

Attackers could gain unauthorized access to user accounts, leading to account takeover and potential data breaches. This could expose sensitive information, allow manipulation of user sessions, or enable further attacks within the system.

Compliance Impact

This vulnerability could lead to unauthorized access to personal or sensitive data, violating GDPR and HIPAA requirements for data protection and access control. Non-compliance may result in legal penalties, fines, or reputational damage.

Mitigation Strategies

Immediately update @better-auth/sso to version 1.6.21 or later to patch the authentication bypass vulnerabilities. Review SSO provider configurations for domain verification mismatches, orphaned accounts, and SAML assertion handling. Disable or restrict access to logout endpoints vulnerable to reflected XSS.

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