Authentication Bypass in Better Auth for TypeScript
CVE-2026-53515

7.1HIGH

Key Information:

Vendor

Better-auth

Status
Better-auth
Sso
Vendor
CVE Published:
15 July 2026

What is CVE-2026-53515?

The Better Auth library for TypeScript contains a significant security flaw in its @better-auth/sso plugin, allowing any member of an organization to attach new SSO providers via the POST /sso/register endpoint. This occurs because the implementation only checks for an existing membership row, neglecting to assert whether the user holds an owner or admin role. Consequently, this oversight enables attackers to register their own OIDC or SAML providers, which can lead to unauthorized provisioning through the /sso/callback/{providerId} endpoint. The issue has been addressed in version 1.6.11.

Affected Version(s)

better-auth >= 1.2.10, < 1.6.11

sso >= 1.2.10, < 1.6.11

References

https://github.com/better-auth/better-auth/security/advis...
x_refsource_CONFIRM
https://github.com/better-auth/better-auth/pull/9220
x_refsource_MISC
https://github.com/better-auth/better-auth/commit/86765f1...
x_refsource_MISC

CVSS V3.1

Score:
7.1
Severity:
HIGH
Confidentiality:
Low
Integrity:
High
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.