OWASP Top 10: Ten Common Web Application Vulnerabilities and Defenses

The OWASP Top 10 distills recurring failure modes seen across web applications globally. It is not a compliance checklist, but a prioritization lens for training, design review, and automated testing—updated periodically as attack economics shift.

Broken access control still dominates many breaches: APIs that trust hidden fields, predictable IDs enabling IDOR, and missing server-side checks on multi-step flows. Treat every endpoint as public; enforce authorization with object-level granularity and test with least-privileged tokens.

Cryptographic failures span more than “wrong cipher.” They include missing TLS, weak key management, logging secrets, client-side “encryption” theater, and storing data you should never retain. Centralize crypto choices and rotate keys with tooling, not tickets alone.

Injection lives in many dialects—SQL, command, LDAP, ORM filters, template engines. Parameterized queries and disciplined APIs beat concatenation. Also watch second-order injection where sanitized input is later executed in another context.

Insecure design is not patchable with a firewall alone. Examples include workflows that skip re-authentication for sensitive actions, chat systems without abuse controls, and marketplaces without fraud modeling. Catch these in threat modeling, not pen tests alone.

Security misconfiguration is the tax of complexity: verbose errors, default credentials, open admin consoles, excessive CORS, missing security headers. Bake hardening baselines into templates and scan infrastructure pre-deploy.

Vulnerable components multiply risk supply-chain-wide. Maintain an SBOM mindset: know direct and transitive dependencies, monitor advisories, and remove unused packages that still receive runtime resolution.

Authentication failures include weak MFA adoption, poor session fixation defenses, naive account recovery, and missing bot protections on login. Align sessions to modern cookie flags and short-lived tokens where appropriate.

Software and data integrity issues appear in unsigned update channels, unsafe deserialization, and build pipelines without verification. Sign artifacts, verify digests, and protect CI with strong SCM controls.

Logging and monitoring failures blind defenders. Log auth decisions, admin actions, and security-relevant errors with tamper-aware storage. Test that alerts route to on-call, not mailbox black holes.

SSRF is particularly dangerous in cloud estates where metadata services and internal admin panels become exfiltration bridges. Block metadata IPs at egress where policy allows, validate URLs against allowlists, and isolate internal HTTP clients.

Process matters: map Top 10 items to your architecture, assign accountable owners, and measure reduction via recurring assessments—not once-a-year theater.

In summary: OWASP Top 10 translates attacker economics into engineering priorities—access control, crypto hygiene, input safety, sound design, hardened configs, fresh dependencies, solid auth, integrity guarantees, observable systems, and safe server-side fetches. Use it to steer budgets, not just to decorate slide decks.