A group of Israeli researchers explored the security of the Visual Studio Code marketplace and managed to "infect" over 100 organizations by trojanizing a copy of the popular 'Dracula Official theme to include risky code. Further research into the VSCode Marketplace found thousands of extensions with millions of installs.
Remembering ActiveX Controls, the Web’s Biggest Mistake: https://www.howtogeek.com/717016/remembering-activex-controls-the-webs-biggest-mistake/
Running JavaScript everywhere is looming as one of the biggest screwups in InfoSec. What do userscript extensions like Grease monkey teach us?