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CVE-2026-53518

HIGH
7.6
CVSS 4.0
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.

Metadata

CVE ID
CVE-2026-53518
State
PUBLISHED
Assigner
GitHub_M
Reserved
2026-06-09 17:30 UTC
Published
2026-07-15 17:17 UTC
Last updated
2026-07-15 18:07 UTC
Primary CWE
CWE-362
CWE-362: Concurrent Execution using Shared Resource with Imp…
Vendor / Product
better-auth / better-auth
Sources
cve.org  ·  NVD

Severity & Metrics

7.6 HIGH CVSS 4.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
SSVC — CISA Coordinator
Exploitation
none
Automatable
no
Tech. Impact
total
Affected products (1)
VendorProductPlatformVersions
better-auth better-auth — >= 1.6.0, < 1.6.11
Weakness (CWE)
CWESourceDescription
CWE-362 cna CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-367 cna CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition
CVSS scores (1)
ScoreSeverityVersionSourceVector
7.6 HIGH 4.0 cna CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
References (3)
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