Content Security Policy (CSP) is a security measure that helps protect websites from attacks such as cross-site scripting (XSS) and data injection. However, if not configured correctly, CSP can break WordPress functionality, causing missing styles, broken JavaScript, and overall disrupted site performance. One common issue arises when the policy is overly restrictive, particularly when the directive includes 'self' without properly allowing required external scripts and resources.
When CSP is set to only allow content from 'self', the browser blocks all resources that originate from external domains unless they are explicitly whitelisted. In a standard WordPress setup, various scripts, stylesheets, and third-party integrations often load from different domains, such as Google Fonts, content delivery networks (CDNs), or API services. If these are not included in the CSP rules, they will fail to load, leading to a broken website.
If CSP is misconfigured, WordPress and various plugins might stop working as expected. Here are some common symptoms:
When these issues occur, it is essential to check your browser’s developer console (press F12 and navigate to the “Console” tab) to identify CSP-related errors.
To resolve this issue, you need to adjust your CSP directives carefully, ensuring that WordPress and its required resources are allowed while maintaining security. Below are step-by-step solutions.
Open your browser’s developer console and look for errors that mention CSP violations. These errors will typically indicate which scripts, styles, or other resources are being blocked.
Modify your CSP header by adding the necessary domains alongside 'self'. You can add this configuration in your web server settings or via a security plugin like WP Security Headers.
Header set Content-Security-Policy "default-src 'self'; script-src 'self' https://cdnjs.cloudflare.com https://ajax.googleapis.com; style-src 'self' https://fonts.googleapis.com; font-src 'self' https://fonts.gstatic.com; img-src 'self' data:;"
add_header Content-Security-Policy "default-src 'self'; script-src 'self' https://cdnjs.cloudflare.com https://ajax.googleapis.com; style-src 'self' https://fonts.googleapis.com; font-src 'self' https://fonts.gstatic.com; img-src 'self' data:;" always;
Ensure you add all required third-party domains for your WordPress installation, plugins, and external scripts.
If you’re unfamiliar with server configurations or prefer an easier approach, consider using a security plugin like:
These plugins allow you to modify CSP settings from the WordPress dashboard without editing server files.
To test your new CSP rules before enforcing them, use Content-Security-Policy-Report-Only. This allows you to see what would be blocked without actually preventing resources from loading.
Header set Content-Security-Policy-Report-Only "default-src 'self'; script-src 'self' https://cdnjs.cloudflare.com ...;"
Check your browser console to verify any remaining violations before enforcing the final policy.
As your website evolves with new plugins, themes, and external services, review and update your CSP policy to prevent future issues while maintaining a strong security posture.
Implementing CSP correctly is crucial for securing your WordPress site, but overly strict policies can break functionality. By analyzing blocked resources, updating your CSP rules, and testing configurations before enforcing them, you can maintain both security and usability. If you’re unsure or need more control, consider using a security plugin to manage CSP settings effectively.
By following these steps, you can restore your WordPress site’s functionality while ensuring it remains protected from malicious threats.