🛡️ Sentinel: [CRITICAL] Fix XSS in DescriptionPreview

[bobdivx]

🚨 Severity: CRITICAL
💡 Vulnerability: The DescriptionPreview component used dangerouslySetInnerHTML to render HTML descriptions received from the backend (or parsed from BBCode) without sufficient sanitization. It only removed literal {} characters.
🎯 Impact: This made it trivial for an attacker to inject malicious scripts (e.g., <script>alert(1)</script>) via the description field, leading to a Cross-Site Scripting (XSS) vulnerability.
🔧 Fix: Imported and applied isomorphic-dompurify (to support both SSR and CSR securely in Astro/Preact) to sanitize the HTML string before passing it to dangerouslySetInnerHTML. Updated the .jules/sentinel.md journal to document this architectural security gap and prevention strategy.
✅ Verification: Verified that building (npm run build) and testing (npm run test) pass. Further verified via a short Node rendering script that malicious script tags are stripped before they ever hit the DOM.

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PR created automatically by Jules for task 6825468937015453122 started by @bobdivx

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Project	Deployment	Actions	Updated (UTC)
popcorn-client	Ready	Preview, Comment	Mar 19, 2026 7:28am

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves a critical XSS vulnerability within the DescriptionPreview component. Previously, the component rendered HTML descriptions without adequate sanitization, allowing for potential malicious script injection. The solution involves integrating isomorphic-dompurify to rigorously sanitize all incoming HTML, thereby securing the application against XSS attacks and ensuring safe content rendering across both server-side and client-side environments.

Highlights

• Critical XSS Vulnerability Fixed: Addressed a critical Cross-Site Scripting (XSS) vulnerability in the DescriptionPreview component.
• HTML Sanitization Implemented: Integrated isomorphic-dompurify to rigorously sanitize HTML content before rendering, effectively preventing malicious script injection.
• Security Documentation Updated: Documented the architectural security gap and the new prevention strategy in the .jules/sentinel.md journal.

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[gemini-code-assist]

Code Review

This pull request effectively addresses a critical Cross-Site Scripting (XSS) vulnerability by integrating isomorphic-dompurify for robust HTML sanitization. The introduction of DOMPurify.sanitize() within the sanitizePreviewHtml function is a crucial step in preventing malicious script injection. The accompanying documentation in .jules/sentinel.md clearly outlines the vulnerability, the lessons learned, and the prevention strategy, which is excellent for maintaining security awareness. The dependency updates in package.json and package-lock.json correctly reflect the addition of the new sanitization library. Overall, this is a well-executed and important security fix.