What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-15 · updated 2026-07-21
• Weakness: CWE-269

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/Sso: before 1.6.11 — fixed in 1.6.11
• better-auth: from 1.2.10 before 1.6.11 — fixed in 1.6.11

How to fix

Upgrade to a fixed version: Better-Auth/Sso 1.6.11; better-auth 1.6.11. Check the vendor advisory for mitigations.

References

• https://github.com/better-auth/better-auth/commit/86765f1597378f5c3deed1b80ca91faac0a6bf00
• https://github.com/better-auth/better-auth/pull/9220
• https://github.com/better-auth/better-auth/releases/tag/v1.6.11
• https://github.com/better-auth/better-auth/security/advisories/GHSA-gv74-j8m3-fg5f

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