Description
Better Auth is an authentication and authorization library for TypeScript. From 1.2.10 until 1.6.11, the @better-auth/sso plugin's POST /sso/register endpoint lets any organization member attach a new SSO provider to that organization because registerSSOProvider checks only for a membership row and does not require an owner or admin role, allowing attacker-controlled OIDC or SAML providers to drive /sso/callback/{providerId} organization provisioning. This issue is fixed in version 1.6.11.
Affected products
better-auth: better-auth\/sso; better-auth: better auth
References4
- github.com/better-auth/better-auth/security/advisories/GHSA-gv7… MitigationVendor Advisory
- github.com/better-auth/better-auth/commit/86765f1597378f5c3deed… Patch
- github.com/better-auth/better-auth/pull/9220 Issue TrackingPatch
- github.com/better-auth/better-auth/releases/tag/v1.6.11 Release Notes
Metrics
- CVSS 3.1
-
7.1
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N - EPSS — exploit probability
- 0% percentile: 37 · as of 15 November 2026
- CWE
- CWE-269CWE-285CWE-863
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.