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Vulnerability record · CVE-2026-53517 · published 15 July 2026

CVE-2026-53517: Better-auth\/oauth-provider race condition vulnerability

Better Auth · Better Auth\/Oauth Provider

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.

8.1 CVSS 3.1 High EPSS 0.42% · top 66.0% CWE-362 · Race conditionCWE-367 · TOCTOU race condition
8.1CVSS 3.1 base score
0.42%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
3References
21 Jul 2026Last modified by NVD

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.

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

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/better-auth/better-auth/commit/c6918ecc9e3a75892169415d7f6c95b591b6a52d Patch
https://github.com/better-auth/better-auth/releases/tag/v1.6.11 Release Notes
https://github.com/better-auth/better-auth/security/advisories/GHSA-392p-2q2v-4372 MitigationVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.6CVE-2026-53513Better-auth\/sso improper input validation vulnerabilityBetter Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the @better-auth/sso plugin's POST /sso/register and POST…EPSS 0.25%9.1CVE-2026-53512Better-auth better auth improper authentication vulnerabilityBetter Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the legacy oidcProvider and mcp plugins expose OAuth toke…EPSS 0.27%8.3CVE-2026-53516Better-auth better auth improper authentication vulnerabilityBetter Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, Better Auth's OAuth callback auto-link gate in handleOAut…EPSS 0.29%7.9CVE-2024-56734Better-auth better auth open redirect vulnerabilityBetter Auth is an authentication library for TypeScript. An open redirect vulnerability has been identified in the verify email endpoint of all versi…EPSS 0.40%7.7CVE-2026-53514Better-auth better auth improper authentication vulnerabilityBetter Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, and in 1.6.14 and later when invitation IDs can be obtain…EPSS 0.20%7.6CVE-2026-53518Better-auth\/oauth-provider race condition vulnerabilityBetter Auth is an authentication and authorization library for TypeScript. From 1.6.0 until 1.6.11, the @better-auth/oauth-provider POST /oauth2/toke…EPSS 0.41%7.6CVE-2026-45337Better-auth better auth improper authorization vulnerabilityBetter Auth is an authentication and authorization library for TypeScript. From 1.6.0 until 1.6.11, the deviceAuthorization plugin treats any authent…EPSS 0.21%7.1CVE-2026-53515Better-auth\/sso improper privilege management vulnerabilityBetter Auth is an authentication and authorization library for TypeScript. From 1.2.10 until 1.6.11, the @better-auth/sso plugin's POST /sso/register…EPSS 0.43%

Source: NIST National Vulnerability Database (record CVE-2026-53517), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.