Better Auth: Account takeover via OAuth auto-link to unverified pre-registered email
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-287.
Summary
Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, Better Auth's OAuth callback auto-link gate in handleOAuthUserInfo accepts implicit account linking when the OAuth provider asserts email_verified: true without requiring the local user row's emailVerified field to also be true, allowing an attacker who pre-registers a victim email through /sign-up/email to bind the victim's OAuth identity to the attacker's account. The same primitive affects one-tap, and emailAndPassword.requireEmailVerification: true does not mitigate the link-time verification change. This issue is fixed in version 1.6.11.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| better-auth | better-auth | before 1.6.11 | 1.6.11 | Patch available | CNA |
| — | better-auth (npm) | before 1.6.11 | 1.6.11 | Patch available | GHSA-g38m-r43w-p2q7 |
- better-auth Vendorbetter-auth Affected before 1.6.11 Fixed in 1.6.11 Patch available CNA
- better-auth (npm) Vendor— Affected before 1.6.11 Fixed in 1.6.11 Patch available GHSA-g38m-r43w-p2q7
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:better-auth:better_auth:*:*:*:*:*:node.js:*:* | before 1.6.11 | Vulnerable | better-auth |
- cpe:2.3:a:better-auth:better_auth:*:*:*:*:*:node.js:*:* Versions before 1.6.11 Vulnerable ·better-auth
Remediation
- Fix · CNA better-auth (better-auth) Fixed in 1.6.11
- Fix · GHSA-g38m-r43w-p2q7 better-auth (npm) Fixed in 1.6.11 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-53516
- 2026-10-03 Alias added: GHSA-g38m-r43w-p2q7
References
Patch 2
Advisory 2
More better-auth Better Auth vulnerabilities
- TI-2025-20000 Beter Auth has an Open Redirect via Scheme-Less Callback Parameter CVSS 4.0MEDIUM 6.9
- TI-2026-38586 Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider and mcp plugins CVSS 4.0CRITICAL 9.1
- TI-2026-38587 Better Auth: Server-side request forgery via unvalidated OIDC endpoints on @better-auth/sso provider registration CVSS 3.1CRITICAL 9.6
- TI-2026-38591 Better Auth OAuth Provider: Refresh Token Rotation Race Condition Allows Concurrent Replay and Token Family Forking CVSS 3.1HIGH 8.1
- TI-2026-38592 Better Auth OAuth Provider: Race Condition in Authorization Code Exchange Enables Multi-Use Code Redemption CVSS 4.0HIGH 7.6
- TI-2026-38588 Better Auth: Unauthorized invitation acceptance via unverified email match in organization plugin CVSS 3.1HIGH 7.7
Sources
- CVE-2026-53516 · CVE Program
- CVE-2026-53516 · NVD
- FIRST EPSS
- GHSA-g38m-r43w-p2q7 · GitHub Advisory Database · CC BY 4.0
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