OWASP API Top 10

API endpoints don't verify that the requesting user owns the resource they're accessing — allowing attackers to access other users' data by changing object IDs.

API authentication mechanisms are weak or improperly implemented — JWT without proper validation, tokens not in httpOnly cookies, or missing token expiration.

API allows users to read or modify object properties they shouldn't have access to — mass assignment, excessive data exposure, or missing field-level access control.

API endpoints without rate limiting, pagination, or resource limits — allowing attackers to exhaust server resources, rack up costs, or extract large datasets.

Admin or privileged API endpoints accessible to regular users — missing role checks allow privilege escalation to administrative functions.

Business-critical flows like registration, password reset, or purchase lack bot protection such as CAPTCHA, rate limiting, or device fingerprinting.

The API fetches a URL provided by the user without validation, allowing attackers to probe internal services, cloud metadata endpoints, or private networks.

APIs expose excessive information through open CORS policies, verbose error messages, missing security headers, or default configurations that were never hardened.

Multiple API versions remain active without documentation or deprecation, leaving old endpoints with known vulnerabilities accessible to attackers.

Your API blindly trusts responses from third-party APIs without validation, allowing attackers to exploit upstream services to compromise your application.