Vulnerability Details CVE-2026-53517
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 33.5%
CVSS Severity
CVSS v3 Score 8.1
References
Products affected by CVE-2026-53517
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cpe:2.3:a:better-auth:better-auth/oauth-provider:1.6.0
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cpe:2.3:a:better-auth:better-auth/oauth-provider:1.6.1
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cpe:2.3:a:better-auth:better-auth/oauth-provider:1.6.10
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cpe:2.3:a:better-auth:better-auth/oauth-provider:1.6.2
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cpe:2.3:a:better-auth:better-auth/oauth-provider:1.6.3
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cpe:2.3:a:better-auth:better-auth/oauth-provider:1.6.4
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cpe:2.3:a:better-auth:better-auth/oauth-provider:1.6.5
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cpe:2.3:a:better-auth:better-auth/oauth-provider:1.6.6
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cpe:2.3:a:better-auth:better-auth/oauth-provider:1.6.7
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cpe:2.3:a:better-auth:better-auth/oauth-provider:1.6.8
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cpe:2.3:a:better-auth:better-auth/oauth-provider:1.6.9
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cpe:2.3:a:better-auth:better_auth:1.4.10
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cpe:2.3:a:better-auth:better_auth:1.4.11
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cpe:2.3:a:better-auth:better_auth:1.4.12
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cpe:2.3:a:better-auth:better_auth:1.4.13
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cpe:2.3:a:better-auth:better_auth:1.4.14
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cpe:2.3:a:better-auth:better_auth:1.4.15
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cpe:2.3:a:better-auth:better_auth:1.4.16
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cpe:2.3:a:better-auth:better_auth:1.4.17
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cpe:2.3:a:better-auth:better_auth:1.4.18
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cpe:2.3:a:better-auth:better_auth:1.4.19
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cpe:2.3:a:better-auth:better_auth:1.4.20
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cpe:2.3:a:better-auth:better_auth:1.4.21
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cpe:2.3:a:better-auth:better_auth:1.4.22
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cpe:2.3:a:better-auth:better_auth:1.4.9
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cpe:2.3:a:better-auth:better_auth:1.5.0
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cpe:2.3:a:better-auth:better_auth:1.5.1
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cpe:2.3:a:better-auth:better_auth:1.5.2
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cpe:2.3:a:better-auth:better_auth:1.5.3
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cpe:2.3:a:better-auth:better_auth:1.5.4
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cpe:2.3:a:better-auth:better_auth:1.5.5
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cpe:2.3:a:better-auth:better_auth:1.5.6
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cpe:2.3:a:better-auth:better_auth:1.5.7
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cpe:2.3:a:better-auth:better_auth:1.6.0
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cpe:2.3:a:better-auth:better_auth:1.6.1
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cpe:2.3:a:better-auth:better_auth:1.6.10
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cpe:2.3:a:better-auth:better_auth:1.6.2
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cpe:2.3:a:better-auth:better_auth:1.6.3
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cpe:2.3:a:better-auth:better_auth:1.6.4
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cpe:2.3:a:better-auth:better_auth:1.6.5
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cpe:2.3:a:better-auth:better_auth:1.6.6
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cpe:2.3:a:better-auth:better_auth:1.6.7
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cpe:2.3:a:better-auth:better_auth:1.6.8
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cpe:2.3:a:better-auth:better_auth:1.6.9