What is the OWASP Top 10 and how does it affect your website?

Sajjad
Security
01 Sep, 2026

The OWASP Top 10 is a regularly updated, community-driven list of the ten most critical security risks facing web applications, published by the Open Worldwide Application Security Project (OWASP). It affects your website because it describes exactly the kinds of weaknesses attackers exploit most often, from broken access control and misconfiguration to injection and vulnerable dependencies, and it has become the baseline that developers, auditors, and hosting providers use to judge whether a site is reasonably secure.

You don't need to be a security specialist to benefit from it. This article explains what OWASP is, how the Top 10 is put together, what each category means in plain language, and what it looks like on a typical website or WordPress install. You'll also get practical steps and code examples for addressing the most relevant risks.

What Is OWASP?

OWASP is a non-profit foundation that produces free, openly available resources for improving software security. Its projects include the Top 10, the Application Security Verification Standard (ASVS), the Cheat Sheet Series, and tools like OWASP ZAP (now maintained as ZAP by Checkmarx). Anyone can use OWASP material, and much of it is written by volunteers from across the security industry.

The Top 10 is OWASP's most famous project. It isn't a formal standard or a certification. It's an awareness document designed to highlight the most important categories of risk so that teams know where to focus.

How the OWASP Top 10 Is Created

The list is updated every few years. OWASP collects vulnerability data contributed by security firms, bug bounty platforms, and organizations, then combines it with a community survey that captures emerging risks the data may not yet reflect. Categories are ranked by factors such as how often they appear, how exploitable they are, and how much impact they have.

The 2021 edition was the long-standing reference for several years. OWASP then published the 2025 edition, which reshuffled some categories and introduced new ones. If you see older documents referring to categories like "Server-Side Request Forgery" as its own entry, they're using the 2021 list. The concepts overlap heavily, so either list will point you toward the same good practices.

The OWASP Top 10 Categories Explained

Below is the 2025 list with an explanation of each risk and how it shows up on real websites.

A01: Broken Access Control

Access control decides who can do what. It's broken when users can reach data or actions they shouldn't, such as viewing another customer's order by changing an ID in the URL, or a subscriber reaching an admin-only function. The 2025 edition also folds server-side request forgery (SSRF) into this category.

On your website, this often appears in plugins that register AJAX or REST API endpoints without checking permissions. In WordPress, every privileged action should check capabilities:

add_action( 'rest_api_init', function () {
    register_rest_route( 'sajjad/v1', '/settings', array(
        'methods'             => 'POST',
        'callback'            => 'sajjad_update_settings',
        'permission_callback' => function () {
            return current_user_can( 'manage_options' );
        },
    ) );
} );

function sajjad_update_settings( WP_REST_Request $request ) {
    $value = sanitize_text_field( $request->get_param( 'value' ) );
    update_option( 'sajjad_setting', $value );
    return rest_ensure_response( array( 'updated' => true ) );
}

The permission_callback is what stops anonymous visitors from calling the endpoint. Never set it to __return_true for anything that changes data.

A02: Security Misconfiguration

This covers insecure default settings, unnecessary features left enabled, verbose error messages, missing security headers, open cloud storage buckets, and directory listings. It moved up in the 2025 ranking because modern applications have so many configurable pieces.

On your website, examples include debug mode left on in production, phpinfo() files left in the web root, or default database credentials. In WordPress, make sure errors aren't shown to visitors:

// In wp-config.php, above "That's all, stop editing!"
define( 'WP_DEBUG', false );
define( 'WP_DEBUG_DISPLAY', false );

A03: Software Supply Chain Failures

This expands the older "Vulnerable and Outdated Components" category. It covers any risk arising from the code and services you depend on: plugins, themes, npm packages, Composer libraries, build tools, and even the update channels themselves.

On your website, this is often the biggest risk of all. An outdated plugin with a known vulnerability, a "nulled" premium theme with a hidden backdoor, or a compromised JavaScript package can all lead to a breach. Keep dependencies updated, remove what you don't use, and install only from trusted sources.

For JavaScript projects, auditing dependencies is a quick first check:

npm audit --omit=dev

For PHP projects using Composer:

composer audit

A04: Cryptographic Failures

Previously called "Sensitive Data Exposure," this category focuses on failing to protect data with proper encryption. It includes sending data over plain HTTP, storing passwords with weak hashing, using outdated algorithms, or hard-coding encryption keys.

On your website, the basics are enforcing HTTPS everywhere, using HSTS, and never storing passwords yourself with MD5 or SHA1. WordPress handles password hashing for its own users (modern versions use bcrypt), so use wp_hash_password() and wp_check_password() rather than rolling your own. In plain PHP, use password_hash() and password_verify().

A05: Injection

Injection happens when untrusted input is sent to an interpreter as part of a command or query. SQL injection is the most famous example, but the category also includes OS command injection, LDAP injection, and, in OWASP's grouping, cross-site scripting (XSS).

On your website, prevention comes down to two rules: use parameterized queries for databases and escape output for the browser.

global $wpdb;

$post_id = absint( $_GET['post_id'] ?? 0 );

$title = $wpdb->get_var(
    $wpdb->prepare( "SELECT post_title FROM {$wpdb->posts} WHERE ID = %d", $post_id )
);

echo '<h2>' . esc_html( $title ) . '</h2>';

A06: Insecure Design

Insecure design is about flaws baked into how a feature was planned, not how it was coded. A password reset flow that reveals whether an email exists, a checkout that trusts the price sent from the browser, or a feature with no rate limiting are all design problems. No amount of careful coding fixes a design that's unsafe by nature.

On your website, this matters most when commissioning custom features. Ask your developer how the feature handles abuse, such as repeated requests, manipulated values, and users acting on other users' data.

A07: Authentication Failures

This covers weaknesses in how users prove who they are: allowing weak passwords, no protection against brute force or credential stuffing, poor session handling, and missing multi-factor authentication.

On your website, practical steps include enforcing strong passwords, enabling two-factor authentication for administrators, limiting login attempts, and logging out idle sessions. Plugins like Wordfence, Solid Security, or Two Factor can help on WordPress.

A08: Software or Data Integrity Failures

This category deals with code and data being trusted without verifying that they haven't been tampered with. Examples include auto-update mechanisms without signature checks, loading scripts from third-party CDNs without integrity checks, and insecure deserialization of untrusted data.

On your website, one simple mitigation is Subresource Integrity (SRI) for any script loaded from a public CDN:

<script
  src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js"
  integrity="sha512-REPLACE_WITH_THE_REAL_HASH_FROM_THE_CDN"
  crossorigin="anonymous"
  referrerpolicy="no-referrer"
></script>

Copy the real integrity value from the CDN's page for that exact file. In PHP, avoid calling unserialize() on user-supplied data; use JSON instead.

A09: Security Logging and Alerting Failures

If you don't log security events and nobody is alerted when something suspicious happens, attacks can go unnoticed for weeks or months. This category covers missing logs, logs that aren't reviewed, and a lack of alerts on events like repeated failed logins or new admin accounts.

On your website, an activity log plugin such as WP Activity Log or Simple History records who did what. Combine it with email or Slack alerts for critical events and uptime monitoring.

A10: Mishandling of Exceptional Conditions

New in 2025, this category covers what happens when things go wrong: unhandled errors, failing "open" instead of failing safely, leaking stack traces, and logic that behaves unpredictably under unusual inputs or resource exhaustion.

On your website, make sure errors are logged privately rather than displayed, and that code defaults to denying access when a check can't be completed. For example, if an API call to verify a licence or permission fails, your code should refuse the action rather than allow it.

How the OWASP Top 10 Affects Your Website

Even if you never read the full OWASP document, it shapes your site's security in several ways.

It Defines What "Reasonably Secure" Means

Clients, auditors, insurers, and payment processors frequently reference the OWASP Top 10 as a baseline. If you're asked whether your site follows security best practices, being able to show that you've addressed these categories is a strong answer.

It Guides Plugin and Theme Quality

Most vulnerabilities reported in WordPress plugins map directly to OWASP categories, especially broken access control, injection (including XSS), and CSRF-style missing nonce checks. Understanding the list helps you judge plugin quality and interpret vulnerability advisories.

It Informs Security Testing

Automated scanners and penetration testers typically organize their findings around OWASP categories. If you receive a security report, the Top 10 gives you the vocabulary to understand it.

It Helps You Brief Developers

When hiring a developer or agency, you can ask how they address each OWASP category. Good developers will have clear answers about input validation, output escaping, capability checks, and dependency management.

A Practical OWASP Checklist for Site Owners

You can translate the Top 10 into a practical checklist:

Access control: Review user roles and remove unnecessary Administrator accounts via Users > All Users.
Configuration: Disable debug display, directory listing, and file editing; add security headers.
Supply chain: Update everything, delete unused plugins and themes, avoid nulled software.
Cryptography: Enforce HTTPS and HSTS; never store passwords in plain text.
Injection: Ensure custom code uses prepared statements and escapes output.
Design: Ask about abuse cases before building custom features.
Authentication: Enforce strong passwords, 2FA, and login rate limits.
Integrity: Use SRI for CDN scripts and avoid unsafe deserialization.
Logging: Install an activity log and set up alerts.
Error handling: Log errors privately and make code fail safely.

Related OWASP Resources

The Top 10 is a starting point. If you want to go further, OWASP offers:

OWASP Cheat Sheet Series: Concise, practical guidance on specific topics like password storage, CSRF prevention, and security headers.
OWASP ASVS: A detailed verification standard you can use to define security requirements for a project.
OWASP API Security Top 10: A separate list focused on risks specific to APIs.
ZAP: A free scanner you can run against your own site (only test sites you own or have permission to test).

FAQ: The OWASP Top 10

OWASP stands for the Open Worldwide Application Security Project. It was previously known as the Open Web Application Security Project, and it's a non-profit foundation that publishes free security resources.

No. It's an awareness document rather than a formal standard. However, many standards, auditors, and contracts reference it, so following it helps you demonstrate good security practice.

It's updated every few years based on new data and community input. The 2021 edition was replaced by the 2025 edition, which reorganized several categories.

Yes. Most reported WordPress vulnerabilities, especially in plugins, fall into OWASP categories like broken access control, injection, and supply chain failures. The same principles apply to any web application.

Cross-site scripting is grouped under the Injection category in recent editions, because it involves untrusted input being interpreted as code, in this case by the visitor's browser.

Not entirely. A security plugin can help with authentication, logging, some misconfiguration, and blocking common exploit attempts, but design flaws and insecure custom code need to be fixed at the source.

Yes. Tools like ZAP can scan sites you own for common issues. Run scans against a staging copy where possible, and never scan sites you don't have permission to test.

Conclusion

The OWASP Top 10 is a concise, trusted summary of the most important web application security risks, from broken access control and misconfiguration to supply chain failures, injection, and poor error handling. It affects your website because attackers exploit exactly these weaknesses, and because clients, auditors, and developers use it as the shared yardstick for what "secure" means.

You don't need to memorize it. Use it as a checklist: keep software updated, check permissions on every privileged action, escape output and prepare queries, enforce strong authentication, log what matters, and fail safely when things go wrong. Working through those ten categories, even at a high level, will put your site well ahead of the automated attacks that target the easy wins.