🛡️ Sentinel: [HIGH] Fix XSS vulnerability in DescriptionPreview

[bobdivx]

🚨 Severity: HIGH
💡 Vulnerability: The DescriptionPreview.tsx component used dangerouslySetInnerHTML to render user-provided HTML and BBCode without proper sanitization. This allowed potential Cross-Site Scripting (XSS) attacks by injecting malicious scripts into the preview area.
🎯 Impact: An attacker could execute arbitrary JavaScript in the context of the user's browser, potentially leading to session hijacking, data theft, or other malicious actions if they managed to upload or display a crafted description.
🔧 Fix: Imported and integrated the isomorphic-dompurify library (which handles both SSR and CSR environments securely) to sanitize the HTML before passing it to dangerouslySetInnerHTML.
✅ Verification: Verified that tests pass via npm test and the build completes successfully via npm run build. Also verified frontend sanitization through a targeted Playwright script demonstrating removal of malicious payload. Added a critical security learning to .jules/sentinel.md as per instructions.

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PR created automatically by Jules for task 8465485573120711493 started by @bobdivx

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Project	Deployment	Actions	Updated (UTC)
popcorn-client	Ready	Preview, Comment	Mar 16, 2026 7:19am

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[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 significantly enhances the application's security by resolving a high-severity Cross-Site Scripting (XSS) vulnerability. The fix involves implementing a comprehensive HTML sanitization process using the isomorphic-dompurify library within the DescriptionPreview.tsx component. This ensures that any user-provided content rendered in the preview area is safe from malicious script injection, thereby protecting users from potential session hijacking or data theft.

Highlights

• High-Severity XSS Vulnerability Fixed: A critical Cross-Site Scripting (XSS) vulnerability in the DescriptionPreview.tsx component has been addressed. Previously, user-provided HTML and BBCode were rendered without proper sanitization, allowing potential script injection.
• Introduced isomorphic-dompurify for HTML Sanitization: The isomorphic-dompurify library was integrated to provide robust and secure HTML sanitization, preventing malicious content from being rendered via dangerouslySetInnerHTML.
• Security Learning Document Added: A new markdown document (.jules/sentinel.md) was added to record the details of this XSS vulnerability, the lessons learned, and the prevention strategies implemented.

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Changelog

• .astro/content.d.ts
  • Updated the import path for content.config.mjs.
• .jules/sentinel.md
  • Added a new security learning document detailing the XSS vulnerability, its impact, and prevention strategies.
• package-lock.json
  • Updated numerous package dependencies to their latest versions.
  • Added isomorphic-dompurify and its associated sub-dependencies.
• package.json
  • Added isomorphic-dompurify as a new project dependency.
• public/VERSION.json
  • Bumped the client version from 1.3.1 to 1.3.4 and the build number from 207 to 210.
• src/components/upload/DescriptionPreview.tsx
  • Imported DOMPurify from isomorphic-dompurify.
  • Applied DOMPurify.sanitize() to the HTML content before rendering it with dangerouslySetInnerHTML.

Activity

• The pull request was automatically created by Jules for a task initiated by @bobdivx.
• Verification included successful npm test and npm run build executions.
• Frontend sanitization was confirmed through a targeted Playwright script.

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[gemini-code-assist]

Code Review

This pull request correctly addresses a high-severity Cross-Site Scripting (XSS) vulnerability in the DescriptionPreview.tsx component. The fix, which involves sanitizing user-provided HTML with isomorphic-dompurify before rendering, is well-implemented and effectively mitigates the security risk. The choice of library is appropriate for an application that uses both Server-Side and Client-Side Rendering. The changes are focused, and the addition of a security learning document is a great practice. The implementation is sound, and I found no issues to report.