Is the Top 10 a checklist I can pass?

No. It is an awareness list of the most critical risk categories. Use it to prioritize learning and testing, and use a standard such as OWASP ASVS to verify requirements in detail.

Why do the rankings change between editions?

They are based on real-world data and community input, so they shift as practices and attack patterns change. A lower rank does not mean a risk disappeared.

The OWASP Top 10:2025 Explained for Developers

Introduction

The OWASP Top 10 is the most widely used awareness document for web application security. The 2025 edition is the eighth, and it reflects what attackers actually exploit: it was built from data covering over 2.8 million applications, plus a community survey. This lesson lists the ten categories, explains what changed, and gives the main defense for each.

Prerequisites

Basic web development knowledge

Step-by-Step Guide

Step 1: See the 2025 list

The Top 10 is a starting point for awareness, not a complete security standard. For a testable standard, see OWASP's Application Security Verification Standard.

A01:2025  Broken Access Control
A02:2025  Security Misconfiguration
A03:2025  Software Supply Chain Failures
A04:2025  Cryptographic Failures
A05:2025  Injection
A06:2025  Insecure Design
A07:2025  Authentication Failures
A08:2025  Software or Data Integrity Failures
A09:2025  Security Logging & Alerting Failures
A10:2025  Mishandling of Exceptional Conditions

Step 2: Know what changed since 2021

There are two new categories and one consolidation. Software Supply Chain Failures (A03) broadens the older vulnerable-and-outdated-components category to cover the whole chain of dependencies, build systems, and distribution. Mishandling of Exceptional Conditions (A10) is new and covers poor error handling, logic errors, and failing open. Server-side request forgery was folded into Broken Access Control. Security Misconfiguration climbed from fifth to second place, while Injection moved from third to fifth.

Step 3: Defend access control and configuration

Broken Access Control stays at number one: enforce authorization on the server for every request, deny by default, and check object ownership, not just login. For Security Misconfiguration, use hardened, repeatable configurations, remove default accounts and unused features, and scan for drift. These two categories are the most common in real applications.

Step 4: Defend the supply chain and cryptography

For supply chain risk, pin and verify dependencies, scan them for known vulnerabilities, generate software bills of materials, and protect your build pipeline. For Cryptographic Failures, use TLS everywhere, strong modern algorithms through well-reviewed libraries, proper key management, and password hashing with Argon2id, as the earlier lessons showed.

Step 5: Defend input, design, identity, and integrity

Prevent Injection with parameterized queries and context-aware output encoding. Address Insecure Design with threat modeling and secure design patterns before coding. For Authentication Failures, use MFA, safe password policy, rate limiting, and secure session handling. For Software or Data Integrity Failures, verify signatures on updates and artifacts, and never deserialize untrusted data unsafely.

Step 6: Defend logging and error handling

For Security Logging and Alerting Failures, log authentication, access control, and validation events, protect the logs, and alert on suspicious patterns so someone acts on them. For Mishandling of Exceptional Conditions, handle errors deliberately, fail closed rather than open, return generic messages to users, never leak stack traces, and test unexpected inputs and failure paths.

FAQs

Is the Top 10 a checklist I can pass?: No. It is an awareness list of the most critical risk categories. Use it to prioritize learning and testing, and use a standard such as OWASP ASVS to verify requirements in detail.
Why do the rankings change between editions?: They are based on real-world data and community input, so they shift as practices and attack patterns change. A lower rank does not mean a risk disappeared.

Summary

The 2025 list adds Software Supply Chain Failures and Mishandling of Exceptional Conditions, and folds SSRF into Broken Access Control. Enforce authorization, harden configuration, secure dependencies, encode and parameterize, and log and fail safely.