CVE-2026-53518

Better Auth is an authentication and authorization library for TypeScript. From 1.6.0 until 1.6.11, the @better-auth/oauth-provider POST /oauth2/token endpoint for the authorization_code grant redeems a single-use authorization code through a non-atomic find-then-delete sequence, allowing two concurrent requests to pass the read step and mint independent access tokens, refresh tokens, and ID tokens; legacy /oauth2/token and /mcp/token paths in oidc-provider and mcp plugins share the same primitive. This issue is fixed in version 1.6.11.

CVSS v3 8.1 HIGH

8.1^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9	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-7w99-5wm4-3g79	Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:better-auth:better-auth\/oauth-provider::::::node.js::*
	cpe:2.3:a:better-auth:better_auth::::::node.js::*

History

No history.

Information

Published : 2026-07-15 18:16

Updated : 2026-07-21 16:03

NVD link : CVE-2026-53518

Mitre link : CVE-2026-53518

CVE.ORG link : CVE-2026-53518

JSON object : View

Products Affected

better-auth

better-auth\/oauth-provider
better_auth

CWE

CWE-362

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CWE-367

Time-of-check Time-of-use (TOCTOU) Race Condition

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