Summary

Root Cause

// packages/server/src/routes/oauth2/index.ts:393-402
res.json({
  success: true,
  message: 'OAuth2 token refreshed successfully',
  credentialId: credential.id,
  tokenInfo: {
    ...tokenData, // ← includes access token!
    has new refresh token: !!tokenData.refresh token,
    expires at: updatedCredentialData.expires at
  }
})

Attack Chain

1. Attacker obtains a credential ID (via Finding 2 / public chatflow leak, or enumeration)
2. Attacker calls POST /api/v1/oauth2-credential/refresh/:credentialId (no auth required)
3. Server decrypts credential, sends refresh request to OAuth provider with user's client secret
4. Server returns the new access token in the response to the attacker
5. Attacker uses the token to access the victim's connected service (Google, Microsoft, etc.)

Docker Validation

Impact

• OAuth2 access token theft for any connected service
• Full access to the victim's third-party accounts (Google, Microsoft, GitHub, etc.)
• Client secret transmitted to OAuth provider during refresh
• Can also be used for DoS by exhausting refresh token quota

Suggested Fix

// Remove from WHITELIST URLS in constants.ts
// Add authentication check in the route handler

Credits

• Shinobi Security - https://github.com/shinobisecurity