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TI-2026-38586 Aliases CVE-2026-53512GHSA-pw9m-5jxm-xr6h

Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider and mcp plugins

Priority MEDIUM 47CWE-287Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-287.

Summary

Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the legacy oidcProvider and mcp plugins expose OAuth token endpoints whose refresh_token grant authenticates only possession of the bound refreshToken row and matching client_id, without verifying the confidential client's client_secret, allowing an attacker with a valid refresh_token to mint access tokens and rotated refresh tokens through /api/auth/oauth2/token or /api/auth/mcp/token. The @better-auth/oauth-provider package is not affected. This issue is fixed in version 1.6.11.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00275 20th percentileScored 2026-11-07
Fix Fixed better-auth (better-auth): 1.6.11better-auth (npm): 1.6.11

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
better-authbetter-authbefore 1.6.111.6.11Patch availableCNA
—better-auth (npm)before 1.6.111.6.11Patch availableGHSA-pw9m-5jxm-xr6h
  • better-auth Vendorbetter-auth Affected before 1.6.11 Fixed in 1.6.11 Patch available CNA
  • better-auth (npm) Vendor— Affected before 1.6.11 Fixed in 1.6.11 Patch available GHSA-pw9m-5jxm-xr6h

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:better-auth:better_auth:*:*:*:*:*:node.js:*:*before 1.6.11Vulnerablebetter-auth
  • cpe:2.3:a:better-auth:better_auth:*:*:*:*:*:node.js:*:* Versions before 1.6.11 Vulnerable ·better-auth

Remediation

  • Fix · CNA better-auth (better-auth) Fixed in 1.6.11
  • Fix · GHSA-pw9m-5jxm-xr6h better-auth (npm) Fixed in 1.6.11 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-53512
  2. 2026-10-03 Alias added: GHSA-pw9m-5jxm-xr6h

References

Patch 2

Advisory 2

Other 2

  • TI-2025-20000 Beter Auth has an Open Redirect via Scheme-Less Callback Parameter CVSS 4.0MEDIUM 6.9
  • TI-2026-38587 Better Auth: Server-side request forgery via unvalidated OIDC endpoints on @better-auth/sso provider registration CVSS 3.1CRITICAL 9.6
  • TI-2026-38591 Better Auth OAuth Provider: Refresh Token Rotation Race Condition Allows Concurrent Replay and Token Family Forking CVSS 3.1HIGH 8.1
  • TI-2026-38590 Better Auth: Account takeover via OAuth auto-link to unverified pre-registered email CVSS 3.1HIGH 8.3
  • TI-2026-38592 Better Auth OAuth Provider: Race Condition in Authorization Code Exchange Enables Multi-Use Code Redemption CVSS 4.0HIGH 7.6
  • TI-2026-38588 Better Auth: Unauthorized invitation acceptance via unverified email match in organization plugin CVSS 3.1HIGH 7.7
See all 9 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences