What Is the OWASP Top 10? Web Security Risks Explained

The OWASP Top 10 is a periodically updated list, published by the Open Web Application Security Project, ranking the most critical security risks facing web applications. It’s not a checklist of specific bugs — it’s a set of risk categories, each broad enough to cover many concrete vulnerabilities, ordered roughly by how common and how damaging they tend to be in real-world applications. For most engineering teams, it’s the default reference point for what “web application security” means in practice.

Why a top-10 list at all

Security is a huge surface area, and most teams don’t have a dedicated security engineer reviewing every line of code. The OWASP Top 10 exists to concentrate limited attention on the risks that account for the overwhelming majority of real breaches — broken access control and injection flaws show up far more often in incident reports than exotic cryptographic attacks. It’s a triage tool: if you can only harden a handful of things, harden these first.

The categories are also useful as a shared vocabulary. When a security review flags “broken access control,” everyone on the team knows roughly what that means and where to look, without needing a shared history of every possible attack technique.

The categories, at a glance

The exact list is revised periodically as attack patterns shift, but the categories have stayed conceptually stable for years. The recurring themes are:

• Broken access control. Users able to act outside their intended permissions — viewing another account’s data by changing an ID in a URL, or reaching an admin endpoint without an admin role. This is consistently the most common category in real audits.
• Cryptographic failures. Sensitive data transmitted or stored without adequate protection — plaintext passwords, weak hashing, or missing HTTPS where it’s needed.
• Injection. Untrusted input executed as code or query logic, the umbrella that includes SQL injection and command injection.
• Insecure design. Security flaws baked into the architecture itself, not fixable by a patch — the kind of thing that requires rethinking a flow, not adding a check.
• Security misconfiguration. Default credentials left in place, verbose error messages leaking internals, unnecessary services left exposed.
• Vulnerable and outdated components. Shipping a library with a known CVE because nobody tracked its version. This is where software supply chain security practices matter most.
• Identification and authentication failures. Weak session handling, predictable tokens, missing protection against credential stuffing.
• Software and data integrity failures. Trusting updates, plugins, or CI/CD pipelines without verifying their integrity — the class of risk behind many supply-chain compromises.
• Security logging and monitoring failures. Breaches that go undetected for months because nothing was watching for the signs.
• Server-side request forgery. A server tricked into making requests on an attacker’s behalf — see what SSRF is for the mechanics.

How the categories map to specific vulnerabilities

It helps to see the relationship between a broad OWASP category and the concrete bug it covers:

OWASP category	Example concrete vulnerability
Injection	SQL injection, command injection
Broken access control	Insecure direct object reference, missing function-level checks
Identification and authentication failures	Session fixation, weak password reset flows
Security misconfiguration	Default admin credentials, exposed debug endpoints
Cryptographic failures	Storing passwords with a fast hash instead of bcrypt or Argon2

Two categories that used to stand on their own — cross-site scripting and cross-site request forgery — are now folded into broader buckets (injection and broken access control, respectively) in newer revisions of the list. The underlying vulnerabilities didn’t disappear; the taxonomy just consolidated around root cause rather than symptom.

How teams actually use it

The Top 10 isn’t a certification you pass once. It shows up in a few recurring workflows:

• Secure code review checklists. Reviewers use the categories as prompts: does this endpoint check authorization, does this query parameterize input, is this response leaking a stack trace.
• Static and dynamic analysis tooling. Most SAST and DAST tools map their findings back to OWASP categories, which makes scan results easier to prioritize and report on.
• Threat modeling. Early in a design, the list is a prompt for “what could go wrong here” across access control, input handling, and configuration — complementary to a broader threat modeling exercise.
• Onboarding. New engineers who’ve never done a security review get a compact, memorable framework rather than an open-ended “think like an attacker.”

What it doesn’t cover

The list is deliberately scoped to web application risks, so it says little about network-level attacks, physical security, or the security of infrastructure itself — a misconfigured WAF or an exposed cloud storage bucket is a real risk that falls partly outside its remit. It’s also a snapshot of common risks, not an exhaustive taxonomy: a novel attack class can exist well before it earns a line item. Treat it as a floor, not a ceiling, for what “secure” means.

It’s also worth remembering the list ranks risk by prevalence and impact across a broad sample of applications — your specific application’s actual risk profile might weight things differently. A public-facing API with no user accounts cares less about session handling and more about rate limiting and input validation; an internal admin tool might have the opposite priorities.

The takeaway

The OWASP Top 10 is a prioritized list of the web’s most common and damaging security risk categories — broken access control, injection, cryptographic failures, and misconfiguration chief among them. It’s not a complete security program on its own, but it’s a well-tested starting point for code review, tooling, and threat modeling, and a shared vocabulary that makes security conversations across a team faster and more precise.