The OWASP Top 10 is the most cited web security standard in procurement and compliance requirements. Updated most recently for 2021 with the 2025 revision in progress, the list reflects real vulnerability patterns observed across thousands of applications. For developers, the value is concrete: each category maps to specific code patterns to avoid.
A01: Broken Access Control. The most prevalent vulnerability in 2024-2025, found in 94% of applications tested. The fix: enforce authorization on every protected endpoint, not just the UI. Check permissions in the controller/handler, not just the frontend. Use a deny-by-default policy — reject requests that don't match an explicit allow rule. Test with automated scanners that walk every endpoint as an unauthenticated user, then as a low-privilege user.
A02: Cryptographic Failures. Transmitting sensitive data over HTTP, using MD5 or SHA-1 for passwords, storing passwords without bcrypt/argon2, using predictable encryption keys. Fix: HTTPS everywhere (HSTS headers), bcrypt with cost factor 12+ for passwords, AES-256-GCM for data at rest, no custom crypto.
A03: Injection (SQL, NoSQL, LDAP, OS commands). Parameterized queries eliminate SQL injection entirely. ORMs like Prisma, SQLAlchemy, and ActiveRecord use parameterized queries by default — the risk is when developers bypass the ORM with raw SQL string concatenation. For OS commands, avoid shell=True in Python and exec() in Node.js; use array-based argument passing instead.
A07: Identification and Authentication Failures. Weak passwords, missing MFA, insecure session management. Delegate authentication to a proven provider (Auth0, Cognito, Supabase Auth) rather than building from scratch. If building your own: rate-limit login attempts, use constant-time comparison for credentials, invalidate sessions on logout.
A10: Server-Side Request Forgery (SSRF). Allowing user-supplied URLs to be fetched by the server lets attackers probe internal services — including cloud metadata endpoints (http://169.254.169.254/latest/meta-data/ returns AWS credentials). Fix: validate and allowlist URL schemes and domains, block requests to RFC-1918 private IP ranges, disable redirects or validate the redirect destination.
AI-generated code introduces OWASP vulnerabilities at scale. Veracode's 2025 analysis found AI-assisted code passes security tests at 47% — below human-written code at 52%. The most common AI mistakes: string concatenation in SQL queries, missing input validation, hardcoded credentials in code samples.