CVE-2026-53512— Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider and mcp plugins
Quick assessment
Affected
better-auth better-auth
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
better-auth Better Auth是better-auth个人开发者开源的一个框架无关认证框架。 Better Auth 1.6.11之前版本存在安全漏洞，该漏洞源于legacy oidcProvider和mcp插件中的OAuth令牌端点未验证机密客户端的client_secret，仅凭refresh_token即可通过/api/auth/oauth2/token或/api/auth/mcp/token生成访问令牌和新的刷新令牌。
Possible ATT&CK Techniques 1 AI
T1528 · Steal Application Access TokenAffected Version Matrix 1
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| better-auth | better-auth | < 1.6.11 |
affected |
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I. Basic Information for CVE-2026-53512
Vulnerability Information
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Vulnerability Title
Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider and mcp plugins
Source: CVE Program / CVE List V5
Vulnerability Description
Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the legacy oidcProvider and mcp plugins expose OAuth token endpoints whose refresh_token grant authenticates only possession of the bound refreshToken row and matching client_id, without verifying the confidential client's client_secret, allowing an attacker with a valid refresh_token to mint access tokens and rotated refresh tokens through /api/auth/oauth2/token or /api/auth/mcp/token. The @better-auth/oauth-provider package is not affected. This issue is fixed in version 1.6.11.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Better Auth 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
better-auth Better Auth是better-auth个人开发者开源的一个框架无关认证框架。 Better Auth 1.6.11之前版本存在安全漏洞，该漏洞源于legacy oidcProvider和mcp插件中的OAuth令牌端点未验证机密客户端的client_secret，仅凭refresh_token即可通过/api/auth/oauth2/token或/api/auth/mcp/token生成访问令牌和新的刷新令牌。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| better-auth | better-auth | < 1.6.11 | - |
|
II. Public POCs for CVE-2026-53512
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2026-53512 (1)
Vendor Advisories for CVE-2026-53512 (1)
Vendor Pages for CVE-2026-53512 (1)
Same Patch Batch · better-auth · 2026-07-15 · 8 CVEs total
| CVE-2026-53513 | 9.6 CRITICAL | Better Auth: Server-side request forgery via unvalidated OIDC endpoints on @better-auth/ss |
| CVE-2026-53516 | 8.3 HIGH | Better Auth: Account takeover via OAuth auto-link to unverified pre-registered email |
| CVE-2026-53517 | 8.1 HIGH | Better Auth OAuth Provider: Refresh Token Rotation Race Condition Allows Concurrent Replay |
| CVE-2026-53514 | 7.7 HIGH | Better Auth: Unauthorized invitation acceptance via unverified email match in organization |
| CVE-2026-45337 | 7.6 HIGH | Better Auth: Device authorization approve and deny accept any authenticated session while |
| CVE-2026-53515 | 7.1 HIGH | Better Auth: Privilege escalation via SSO provider registration: missing admin role check |
| CVE-2026-53518 | Better Auth OAuth Provider: Race Condition in Authorization Code Exchange Enables Multi-Us |
IV. Related Vulnerabilities
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Same vendor: better-auth
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Better Auth before 1.4.5 Path Normalization Bypass via rou3 -
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Same weakness: CWE-287
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V. Comments for CVE-2026-53512
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