Auth bypass in @Better-Auth Sso
CVE-2026-53515
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.
Vulnerability class: Privilege Escalation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N.
EPSS exploit prediction
EPSS: 0.004 (35.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 35.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- @Better-Auth Sso — versions >= 1.2.10, < 1.6.11
- Better-Auth — versions >= 1.2.10, < 1.6.11
- Better-Auth Better Auth
- Better-Auth Better-Auth\/sso
Weakness classification (CWE)
References
- github.com/better-auth/better-auth/security/advisories/GHSA-gv74-j8m3-fg5f (Mitigation, Vendor Advisory)
- github.com/better-auth/better-auth/pull/9220 (Patch, Issue Tracking)
- github.com/better-auth/better-auth/commit/86765f1597378f5c3deed1b80ca91faac0a6b… (Patch)
- github.com/better-auth/better-auth/releases/tag/v1.6.11 (Release Notes)
Frequently asked questions
- What is CVE-2026-53515?
- CVE-2026-53515 is a high-severity vulnerability in @Better-Auth Sso, classified under Improper Privilege Management. CVSS score: 7.1/10. Published 2026-07-15.
- How severe is CVE-2026-53515?
- High severity. CVSS v3 base score is 7.1 out of 10.