Review reviewHigh

CVE-2026-53515

better-auth better-auth, sso, better-auth/sso

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: 7.1
EPSS: 0.24%
CISA KEV: Not listed
Published: 2026.07.16

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.24%

Technical severityCVSS 7.1

Vulnerability overview

Affected product and versions

Product: better-auth better-auth, sso, better-auth/sso
Affected versions: >= >= 1.2.10, < 1.6.11, >= 1.2.10 < 1.6.11
Fixed versions: 1.6.11

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that better-auth better-auth, sso, better-auth/sso and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
CWE: CWE-269, CWE-285, CWE-863