CVE-2026-53515: Better Auth: Privilege escalation via SSO provider registration: missing admin role check in @better-auth/sso

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.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

Attack vector

Network

Complexity

Low

Privileges

Low

User interaction

None

Confidentiality

Low

Integrity

High

Availability

None

Scope

Unchanged

Exploitation

Is it being used?

Exploit prediction (EPSS)0.4% · higher than 37% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

BE

better-auth · better-auth

>= 1.2.10, < 1.6.11 · source: vendor

SS

sso · @better-auth

>= 1.2.10, < 1.6.11 · source: vendor

BA

Better Auth · Better-auth

1.2.10 before 1.6.11 · source: NVD

BE

Better-auth/sso · Better-auth

before 1.6.11 · source: NVD