OWASP Top 10 for Small Business: The Vulnerabilities That Actually Affect You

What Is OWASP?

The Open Worldwide Application Security Project (OWASP) is a nonprofit foundation that works to improve software security. Their most well-known publication is the OWASP Top 10 — a list of the ten most critical security risks to web applications, updated every few years based on real-world data.

The current version (2021) was compiled from data covering over 500,000 applications. It is the de facto standard for web application security — referenced by compliance frameworks (PCI-DSS, SOC 2), security tools, and development teams worldwide.

But here is the problem: the OWASP Top 10 is written for enterprise security teams. If you run a small business website — a WordPress site, a Shopify store, a Next.js app, or a static site with a contact form — much of the guidance feels inaccessible.

This guide translates the OWASP Top 10 into practical terms for small businesses, focusing on the vulnerabilities that are most likely to affect you and the fixes that require the least effort.

Why Small Businesses Should Care

"We are too small to be a target" is the most dangerous assumption in cybersecurity. The reality:

• Automated bots do not discriminate by company size — they scan every website on the internet
• Small businesses have weaker defenses — making them easier targets than large enterprises
• Supply chain attacks — your compromised website can be used to attack your customers or partners
• Compliance is becoming mandatory — GDPR applies to any business handling EU data, regardless of size

The OWASP Top 10 is not just for banks and government agencies. These vulnerabilities exist on WordPress blogs, small e-commerce sites, and landing pages alike.

A01: Broken Access Control

What it is: Users can access data or perform actions they should not be authorized for.

How it affects small businesses:

• A customer can view another customer's order by changing the ID in the URL (/order/123 → /order/124)
• An anonymous user can access admin pages because they are only hidden in the navigation, not actually restricted
• API endpoints return data without checking who is asking

How to fix it:

• Always check authorization server-side, not just in the UI
• Use your framework's built-in access control (WordPress roles, Next.js middleware)
• Test by trying to access pages and APIs as a different user or while logged out

# Quick test: can you access admin pages while logged out?
curl -I https://yoursite.com/wp-admin/
curl -I https://yoursite.com/admin/
curl -I https://yoursite.com/dashboard/

A02: Cryptographic Failures

What it is: Sensitive data is not properly encrypted — in transit or at rest.

How it affects small businesses:

• Your site does not use HTTPS (or has a misconfigured SSL certificate)
• Customer passwords are stored in plain text
• You email sensitive data in plain text
• Backups containing customer data are not encrypted

How to fix it:

• Enable HTTPS — most hosting providers offer free SSL through Let's Encrypt
• Never store passwords in plain text — use bcrypt or your CMS's built-in password hashing
• Enable HSTS — forces HTTPS and prevents downgrade attacks
• Check your SSL configuration — run a scan to verify your certificate and protocols

This is one of the easiest OWASP categories to address. HTTPS and proper SSL configuration are table stakes in 2026.

A03: Injection

What it is: An attacker sends malicious data through a form or URL that gets executed as code.

The most common types:

• SQL Injection — manipulating database queries through input fields
• Cross-Site Scripting (XSS) — injecting JavaScript that runs in other users' browsers
• Command Injection — executing system commands through application inputs

How it affects small businesses:

• A contact form that does not sanitize input could be used to steal your database
• A search bar vulnerable to XSS could be used to steal customer sessions
• WordPress plugins with SQL injection vulnerabilities are discovered regularly

How to fix it:

• Keep your CMS and plugins updated — most injection vulnerabilities are patched quickly
• Use parameterized queries — if you write custom database code, never concatenate user input into SQL strings
• Validate all input — check that email fields contain emails, numbers are numbers, and text does not contain script tags

// VULNERABLE — never do this
$query = "SELECT * FROM users WHERE email = '" . $_POST['email'] . "'";

// SAFE — parameterized query
$stmt = $pdo->prepare("SELECT * FROM users WHERE email = ?");
$stmt->execute([$_POST['email']]);

A05: Security Misconfiguration

This is the big one for small business websites. Security misconfiguration is the most common vulnerability found in small business web applications, and the one ZeriFlow catches most frequently.

What it is: Default configurations, incomplete configurations, or overly permissive settings that leave your site exposed.

Common examples on small business sites:

• Missing security headers — no HSTS, no CSP, no X-Content-Type-Options
• Default credentials — WordPress admin using "admin/admin"
• Directory listing enabled — visitors can browse your server's file structure
• Verbose error messages — stack traces and database errors shown to users
• Unnecessary features enabled — XML-RPC on WordPress, debug mode in production
• Server version exposed — "Apache/2.4.41" or "nginx/1.18.0" in headers

How to fix it:

1. 1Add security headers — see our guide to fixing security headers
2. 2Disable directory listing:

# Apache — .htaccess
Options -Indexes

# Nginx
autoindex off;

1. 1Remove server version headers:

# Nginx
server_tokens off;

# Apache
ServerTokens Prod
ServerSignature Off

1. 1Disable XML-RPC on WordPress (if you do not use the mobile app or Jetpack):

// functions.php
add_filter('xmlrpc_enabled', '__return_false');

1. 1Run a security scan — ZeriFlow checks specifically for misconfigurations and gives you step-by-step remediation instructions.

A06: Vulnerable and Outdated Components

What it is: Using software libraries, plugins, or frameworks with known security vulnerabilities.

How it affects small businesses:

• WordPress plugins account for 98% of WordPress vulnerabilities (WPScan data)
• An outdated jQuery library on your site could enable XSS attacks
• A vulnerable PHP version on your hosting could be exploited remotely

How to fix it:

• Update everything regularly — CMS, plugins, themes, server software
• Remove unused plugins — if you are not using it, delete it
• Enable automatic updates where available (WordPress supports this for plugins)
• Check plugin reputation — before installing, check the last update date, number of installations, and reviews

A07: Identification and Authentication Failures

What it is: Weaknesses in how your site handles user login and session management.

How it affects small businesses:

• No rate limiting on login pages — attackers can brute-force passwords
• No two-factor authentication — passwords alone are not enough
• Session tokens do not expire — a stolen session stays valid indefinitely
• Password reset flows that leak information ("No account found with this email")

How to fix it:

• Enable 2FA for all admin accounts
• Use a login rate limiter — WordPress plugins like "Limit Login Attempts Reloaded" or "Wordfence"
• Set session timeouts — sessions should expire after a reasonable period
• Use generic error messages — "Invalid email or password" instead of specifying which was wrong

The Others (Brief)

The remaining OWASP Top 10 entries are less commonly an issue for small business websites, but worth knowing:

• A04: Insecure Design — fundamental design flaws. Less relevant if you use a well-established CMS.
• A08: Software and Data Integrity Failures — using untrusted plugins or CDN scripts without integrity checks. Use integrity attributes on script tags when loading from CDNs.
• A09: Security Logging and Monitoring Failures — not knowing when you have been breached. Set up basic monitoring and log review.
• A10: Server-Side Request Forgery (SSRF) — primarily affects custom applications with URL-fetching features. Less relevant for standard CMS sites.

Your Priority Action List

Based on the OWASP Top 10 and what actually affects small businesses, here is your priority order:

Scan Your Site Against OWASP Issues

The fastest way to check your site against the most common OWASP vulnerabilities is to run an automated scan. ZeriFlow checks your website across 12+ categories that map directly to OWASP concerns — SSL/TLS (A02), security headers (A05), cookies (A07), information disclosure (A05), and more.

Run a free scan at zeriflow.com to see how your site scores against industry standards. You will get a score out of 100 and specific, actionable recommendations to fix each issue — starting with the highest-impact items.