Better Auth OAuth Provider: Refresh Token Rotation Race Condition Allows Concurrent Replay and Token Family Forking

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Summary

CVECVE-2026-53517
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-15 18:16:48 UTC
Updated2026-07-15 20:54:43 UTC
DescriptionBetter 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.

Risk And Classification

Primary CVSS: v3.1 8.1 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS: 0.004130000 probability, percentile 0.334130000 (date 2026-07-16)

Problem Types: CWE-362 | CWE-367 | CWE-362 CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') | CWE-367 CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
3.1CNADECLARED8.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Better-auth Better-auth affected >= 1.4.8-beta.7, < 1.6.0 Not specified
CNA @better-auth Oauth-provider affected >= 1.6.0, < 1.6.11 Not specified

References

ReferenceSourceLinkTags
github.com/better-auth/better-auth/releases/tag/v1.6.11 [email protected] github.com
github.com/better-auth/better-auth/commit/c6918ecc9e3a75892169415d7f6c95... [email protected] github.com
github.com/better-auth/better-auth/security/advisories/GHSA-392p-2q2v-4372 [email protected] github.com
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