Troubleshooting CSP Issues

1. Introduction

Content Security Policy (CSP) is a security feature that helps prevent various attacks, such as Cross-Site Scripting (XSS) and data injection attacks. This lesson covers troubleshooting common CSP issues that may arise during implementation.

2. Understanding CSP

CSP is defined via HTTP headers or a `` tag and allows you to control resources the user agent is allowed to load for a given page. Here’s a simple CSP directive:

Content-Security-Policy: default-src 'self';

This directive allows the page to load resources only from the same origin.

3. Common CSP Issues

• Blocked inline scripts/styles due to `unsafe-inline` restrictions.
• Blocked resources from third-party domains not whitelisted.
• Errors in browser console indicating violations of CSP rules.

4. Troubleshooting Steps

Follow these steps to troubleshoot CSP issues:

1. Check the browser console for CSP violation reports.
2. Identify which resources are being blocked.
3. Review your CSP directives to ensure all required sources are whitelisted.
4. Modify the CSP policy as needed and test again.

Flowchart for Troubleshooting

graph TD;
    A[Start] --> B{CSP Error?};
    B -- Yes --> C[Check console logs];
    B -- No --> D[No action needed];
    C --> E[Identify blocked resources];
    E --> F[Review CSP directives];
    F --> G{Need changes?};
    G -- Yes --> H[Modify CSP];
    G -- No --> I[End];
    H --> J[Test again];
    J --> B;
    I --> K[End];
    

5. Best Practices

• Use `report-uri` or `report-to` for monitoring CSP violations.
• Avoid using `unsafe-inline` and `unsafe-eval` where possible.
• Regularly review and update your CSP policy as your application evolves.

6. FAQ