tl;dr; Stored XSSes in Facebook wall by embedding an external video with Open Graph. When a user clicks to play the video, the XSS executes on facebook.com Introduction I reported multiple stored XSS on Facebook wall in April 2017. These stored XSS vulnerabilities were also present in WordPress so I waited for WordPress to patch it before… Read More


Last week, I disclosed the existence of an unpatched Flash vulnerability on WordPress (https://opnsec.com/2017/10/cve-2016-9263-unpatched-xsf-vulnerability-in-wordpress/). Today, I disclose technical details about this vulnerability. However, contrary to what I announced before, I won’t provide a POC nor enough technical details to allow attackers to exploit it. Responsible disclosure of unpatched vulnerabilities is never easy, and I’m trying… Read More


Please patch this issue on your WordPress websites immediately and ask WordPress to release a patched version before I publicly release technical details about this on Oct 19th 2017 What is the vulnerability ? There is an unpatched vulnerability in latest and older WordPress releases. The vulnerability is a cross-domain Flash injection (XSF), which impact… Read More


IV. Flash based XSSes on Youtube iframe api I’m happy that people found my previous posts on Youtube Flash vulnerabilities interesting, and I will keep posting new write-ups. This time I will disclose 3 Flash based XSSes on the new Youtube html5 api (with Flash fallback). Youtube html5 api is called Youtube iframe api, because… Read More


III. XSF via loaderinfo.url redefinition Let’s have a look at how the Main App loads the Modules : The url of the module is dynamically generated by the main app by using it’s own url (2) and replacing the filename (watch_as3.swf) by the module filename (subtitles.swf) (3). This allows to handle multiple versions on the… Read More


II. XSF via appLoader In Part 1, I introduced an information leakage vulnerability in Youtube. In this part I will disclose a more severe vulnerability that allows arbitrary Flash code execution in youtube.com. This type of vulnerability is very similar to XSS except we execute Flash code instead of Javascript. It is called Cross-Site Flashing… Read More


Why Flash Security still matters? Flash is still an active threat. In 2017, I reported Flash vulnerabilities to Facebook, Youtube, WordPress, Yahoo, Paypal and Stripe. Over the last 3 years, I reported more than 50 Flash vulnerabilities to Bug Bounty programs, earning more than 80k $ in rewards. And there are many more I didn’t… Read More