CVE-2026-53517— Better Auth OAuth Provider: Refresh Token Rotation Race Condition Allows Concurrent Replay and Token Family Forking
Quick assessment
Affected
better-auth better-auth
Exploitation
Public or AI PoC available; prioritize validation
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的防病毒反病毒产品。 Better Auth存在竞争条件问题漏洞，该漏洞源于@better-auth/oauth-provider的POST /oauth2/token端点对refresh_token grant执行非原子读取、验证、撤销和签名序列，可能导致具有相同父刷新令牌的并发请求通过已撤销检查并创建分叉的刷新令牌族。以下版本受到影响：1.4.8-beta.7及之前版本和1.6.0版本至1.6.11版本之前版本。
Possible ATT&CK Techniques 1 AI
T1528 · Steal Application Access TokenAffected Version Matrix 2
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| @better-auth | oauth-provider | >= 1.6.0, < 1.6.11 |
affected |
| better-auth | better-auth | >= 1.4.8-beta.7, < 1.6.0 |
affected |
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I. Basic Information for CVE-2026-53517
Vulnerability Information
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Vulnerability Title
Better Auth OAuth Provider: Refresh Token Rotation Race Condition Allows Concurrent Replay and Token Family Forking
Source: CVE Program / CVE List V5
Vulnerability Description
Better Auth is an authentication and authorization library for TypeScript. From 1.4.8-beta.7 until 1.6.11, the @better-auth/oauth-provider POST /oauth2/token endpoint on the refresh_token grant performs a non-atomic read, validate, revoke, and mint sequence on the oauthRefreshToken row, allowing concurrent requests with the same parent refresh token to pass the revoked check and create forked refresh-token families; the vulnerable range also includes embedded better-auth plugin versions before 1.6.0. This issue is fixed in version 1.6.11.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用共享资源的并发执行不恰当同步问题(竞争条件)
Source: CVE Program / CVE List V5
Vulnerability Title
Better Auth 竞争条件问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
better-auth better-auth是better-auth的防病毒反病毒产品。 Better Auth存在竞争条件问题漏洞，该漏洞源于@better-auth/oauth-provider的POST /oauth2/token端点对refresh_token grant执行非原子读取、验证、撤销和签名序列，可能导致具有相同父刷新令牌的并发请求通过已撤销检查并创建分叉的刷新令牌族。以下版本受到影响：1.4.8-beta.7及之前版本和1.6.0版本至1.6.11版本之前版本。
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 | >= 1.4.8-beta.7, < 1.6.0 | - |
|
| @better-auth | oauth-provider | >= 1.6.0, < 1.6.11 | - |
|
II. Public POCs for CVE-2026-53517
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POC
Premium
Qwen3.6-35B-A3B
· 12172 chars
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III. Intelligence Information for CVE-2026-53517
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Patches & Fixes for CVE-2026-53517 (1)
Vendor Advisories for CVE-2026-53517 (1)
Vendor Pages for CVE-2026-53517 (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-2026-53514 | 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 | |
| CVE-2026-53512 | Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider |
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