link-shim-bypass

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A critical XSS vulnerability on Facebook's CDN was achieved by encoding malicious JavaScript into PNG IDAT chunks, uploading the image as an advertisement, then serving it with an .html extension to trigger HTML interpretation via MIME sniffing. The attacker leveraged document.domain to access the fb_dtsg CSRF token from www.facebook.com and bypass LinkShim protections.

Facebook Akamai akamaihd.net fbcdn.net photo.facebook.com fnt.pe phwd
whitton.io · devanshbatham/Awesome-Bugbounty-Writeups · 20 hours ago · details