CVE-2026-53518
Better Auth OAuth Provider: Race Condition in Authorization Code Exchange Enables Multi-Use Code Redemption
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.
INFO
Published Date :
July 15, 2026, 6:16 p.m.
Last Modified :
July 15, 2026, 7:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update @better-auth/oauth-provider to version 1.6.11.
- Apply security patches for oidc-provider and mcp plugins.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-53518.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-53518 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-53518
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-53518 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-53518 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 15, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-53518', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-07-15T18:07:40.302581Z'} -
New CVE Received by [email protected]
Jul. 15, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'better-auth', 'product': 'better-auth', 'versions': [{'status': 'affected', 'version': '>= 1.6.0, < 1.6.11'}]}] Added 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. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-362 Added CWE CWE-367 Added Reference https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9 Added Reference https://github.com/better-auth/better-auth/releases/tag/v1.6.11 Added Reference https://github.com/better-auth/better-auth/security/advisories/GHSA-7w99-5wm4-3g79