OWASP Top 10

What is the OWASP Top 10?

The OWASP Top 10 is a widely-referenced awareness document, published by the Open Worldwide Application Security Project, that ranks the ten most critical security risks to web applications. Updated periodically (major revisions in 2013, 2017, 2021, with the next iteration reflecting current threats), it’s compiled from industry data and expert consensus, and it has become the de facto common baseline for web application security — a shared vocabulary that developers, security teams, auditors, and compliance frameworks all point to when discussing “the important web risks to defend against.” If you build web applications, the OWASP Top 10 is the canonical starting list of what can go wrong.

What it covers — the recurring categories

The Top 10 is organized as categories of risk rather than individual bugs, and the recurring themes are worth knowing because they capture where real breaches come from. Long-standing entries include Injection (untrusted input interpreted as code — SQL injection, command injection, and XSS folds in here), Broken Access Control (users accessing things they shouldn’t — which rose to the #1 risk in 2021, reflecting how common and damaging authorization failures are, e.g., insecure direct object references and missing least-privilege enforcement), Cryptographic Failures (weak or missing encryption exposing sensitive data), Security Misconfiguration (insecure defaults, unnecessary features, exposed error details), Vulnerable and Outdated Components (using dependencies with known CVEs — the supply-chain risk behind incidents like Log4Shell), Identification and Authentication Failures (weak login, session handling), Server-Side Request Forgery (SSRF) (added in 2021 as cloud architectures made it critical), and Insecure Design (a 2021 addition emphasizing that security must be built in from the design phase — via threat modeling — not bolted on). The exact list and ranking shift between editions as the threat landscape evolves, which is itself informative: the movement of categories (access control rising, new entries like SSRF appearing) tracks how attacks and architectures change.

How to use it well — and its limits

The OWASP Top 10 is enormously valuable as awareness, education, and a baseline: it’s excellent for training developers on the risks that matter most, for establishing a shared security vocabulary, and as a floor for secure development. But its intended use is frequently misunderstood, and the honest guidance is important. First, it’s an awareness document, not a complete security standard or a certification checklist — OWASP itself is explicit that covering the Top 10 is a starting point, not a guarantee of security; a real application has risks beyond ten categories, and “we’re not on the Top 10 list” is not the same as “we’re secure.” Treating it as an exhaustive checklist to tick off breeds a false sense of completeness. (For a more comprehensive standard, OWASP offers the ASVS — Application Security Verification Standard — which is the detailed requirements document the Top 10 is not.) Second, the Top 10 describes categories, not your specific application — you still have to do the work of finding your vulnerabilities through threat modeling, code review, scanning, and penetration testing; the list tells you what kinds of things to look for, not where they are in your code. Third, security is about building it in, not checking it off — the 2021 addition of “Insecure Design” underscores that many of these risks stem from design decisions, so awareness must translate into secure development practices, not a late-stage audit against a list. The recurring mistakes: treating the Top 10 as a complete/sufficient security checklist (it’s a baseline), assuming “compliant with the Top 10” means “secure,” and using it as a substitute for actually testing and threat-modeling your own application rather than as the awareness foundation it’s meant to be.

What people get wrong

• Treating it as a complete checklist — it’s an awareness document and a baseline, not an exhaustive standard; covering the Top 10 doesn’t mean an app is secure (use ASVS for thorough requirements).
• “Not on the list = secure”: real applications have risks beyond ten categories — the Top 10 tells you what kinds of flaws matter, not whether your specific app has them.
• Using it instead of testing your app — the list is a guide to what to look for; you still need threat modeling, code review, scanning, and pen testing to find where those risks actually live.

Primary source: OWASP Top 10