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Better Auth\/oauth ProviderApplication · Better Auth

CVE-2026-53517

HIGH · 8.1 CVSS v3.1 Published 2026-07-15
Fix available
A fix is available. Upgrade to 1.6.11 or later.
See remediation →
87/100
Remediation priority · High
Remotely reachable Zero-click 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A race condition in Better Auth's OAuth refresh token flow allows concurrent requests using the same refresh token to bypass revocation checks. The non-atomic sequence of read, validate, revoke, and mint operations on oauthRefreshToken rows enables attackers to create forked refresh-token families and potentially maintain persistent access.

MitigationUpgrade @better-auth/oauth-provider to version 1.6.11 or later to receive the patch that makes the refresh token operations atomic.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Better Auth\/oauth ProviderApplication
Affected:>= 1.6.0, < 1.6.11
Better AuthApplication
Affected:>= 1.4.9, < 1.6.11= 1.4.8

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check better-auth package version
    Run 'npm list better-auth' or check package.json to identify the installed version of better-auth
    Affected if Installed version is >= 1.4.9 and < 1.6.11, or exactly 1.4.8
  2. Check @better-auth/oauth-provider package version
    Run 'npm list @better-auth/oauth-provider' or check package.json to identify the installed version
    Affected if Installed version is >= 1.6.0 and < 1.6.11
  3. Verify OAuth provider is configured
    Inspect your Better Auth configuration for oauthProvider or any OAuth-related setup. Look for refresh token configuration in your auth initialization code
    Affected if OAuth refresh token flow is enabled in your application
  4. Check database for oauthRefreshToken storage
    Examine your database schema or query the database for an oauthRefreshToken table/collection to confirm refresh tokens are being stored
    Affected if oauthRefreshToken records exist in your database, indicating active use of OAuth refresh tokens

You are affected if you are using Better Auth with OAuth refresh tokens and your installed version falls within the vulnerable ranges: better-auth < 1.6.11 (and not 1.5.x series if that exists) or @better-auth/oauth-provider between 1.6.0 and 1.6.10 inclusive.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.6.11 or later
Fixed in 1.6.11
Interim mitigation

Upgrade @better-auth/oauth-provider to version 1.6.11 or later to receive the patch that makes the refresh token operations atomic.

Recommended fix High confidence

1.6.11

  1. Upgrade @better-auth/oauth-provider to version 1.6.11 or later by running: npm install @better-auth/oauth-provider@^1.6.11 or yarn add @better-auth/oauth-provider@^1.6.11
  2. If using embedded better-auth plugins, ensure all plugin versions are updated to 1.6.0 or later
  3. Verify the upgrade by checking the installed version with npm list @better-auth/oauth-provider or equivalent

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Better Auth\/oauth Provider Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing10.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,580
Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-53517 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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