Hacking a note-taking app from BITSCTF 2025. The exploit leverages a UTF-8 to ASCII conversion issue to inject XSS that remains unnoticed by DOMPurify and uses angular.js from Cloudflare CDN to bypass CSP restrictions.
The challenge involved crafting an XSS payload to extract a flag from an HTML tag, leveraging a vulnerability in the processing of uploaded .xlsx files and exploiting xmlattr vulnerability in Jinja2.