CVE-2026-53518
Received
Received - Intake
Authentication Code Reuse in Better Auth Library
Vulnerability report for CVE-2026-53518, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-07-15
Last updated on: 2026-07-15
Assigner: GitHub, Inc.
Description
Description
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 Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| better-auth | better-auth | to 1.6.11 (exc) |
| better-auth | better-auth | to 1.6.0 (exc) |
| better-auth | oauth-provider | to 1.6.11 (exc) |
| better-auth | oauth-provider | From 1.6.0 (inc) |
| better-auth | oidc-provider | From 1.4.8-beta.7 (inc) |
| better-auth | mcp | From 1.4.8-beta.7 (inc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-362 | The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently. |
| CWE-367 | The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. |
