This document outlines the security considerations and known issues for the PDF & Image Editor web application.

Severity: Medium
Status: Acknowledged (By Design)

Description: The application loads three external JavaScript libraries from CDN without Subresource Integrity (SRI) hashes:

• PDF.js from cdnjs.cloudflare.com
• pdf-lib from unpkg.com
• Fabric.js from cdnjs.cloudflare.com

Rationale: This is a conscious design decision to keep the application:

• Simple: No build step required, just open index.html in a browser
• Up-to-date: Can easily update to latest library versions
• Lightweight: No need to bundle large libraries in the repository

Mitigations Applied:

1. Added crossorigin="anonymous" to prevent credential leakage
2. Added referrerpolicy="no-referrer" to protect user privacy
3. Using well-known, reputable CDN providers
4. All file processing happens client-side (no server-side attacks possible)

Recommendations for Production:

1. Self-host libraries: Download and serve libraries from your own domain
2. Add SRI hashes: Include integrity attributes for all external scripts
3. Implement CSP: Add Content Security Policy headers to restrict script sources
4. Regular updates: Monitor and update library versions for security patches

Example for production deployment:

<script src="/vendor/pdf.min.js" 
        integrity="sha384-[hash-here]" 
        crossorigin="anonymous"></script>

• No Server Required: All PDF and image processing happens in the browser
• No Data Upload: User files never leave their device
• Privacy Preserving: No tracking, analytics, or data collection
• Offline Capable: Works without internet after initial load (via Service Worker)

• File type validation for uploads (PDF for PDF editor, images for image editor)
• Error handling with user-friendly messages
• Safe file handling using FileReader API

• Uses standard Web APIs (FileReader, Canvas, Blob)
• Service Worker for PWA functionality
• No eval() or dangerous code execution patterns

1. CDN Dependency: Requires internet connection for initial load to fetch CDN resources
2. Browser Compatibility: Requires modern browser with ES6+ support
3. No Server-Side Validation: All validation is client-side (acceptable for client-only app)

• Client-side code execution
• User data privacy
• External dependency integrity

• Server-side attacks (SQL injection, XSS, etc.)
• Authentication/Authorization
• Data persistence/storage
• API security

1. Use HTTPS: Always access the application over HTTPS
2. Trusted Source: Only use the application from trusted sources
3. Browser Updates: Keep your browser updated for latest security patches
4. Sensitive Data: For highly sensitive documents, consider self-hosting with SRI hashes

For production deployments, consider:

1. Self-hosting all external libraries
2. Implementing Content Security Policy
3. Adding Subresource Integrity hashes
4. Setting up automated security scanning
5. Regular dependency updates
6. HTTPS enforcement

This application has been designed with security and privacy in mind. The identified CodeQL alerts about CDN integrity are acknowledged and documented. For a simple, client-side web application with no backend, the current security posture is appropriate. Users with higher security requirements should follow the production deployment recommendations.

Overall Security Assessment: ✅ Acceptable for intended use case (client-side PDF/image editing tool)

Last Updated: 2026-02-15