How should browsers mitigate Proxy-related security issues? · Issue #272 · tc39/ecma262There's a security issue on the web with ES2015 Proxies where a cross-origin request can be made to load some ECMAScript code, and this request can leak some information across origins due to the existence of Proxies. Details can be found here: https://code.google.com/p/chromium/issues/detail?id=399951 . The short story is that the Proxy can be put in the prototype chain of the global object, and
136452 – [Cocoa][Win] Enable of X-Content-Type-Options: nosniff header
Web Application Exploits and Defenses
https://www.mbsd.jp/Whitepaper/xssi.pdf
471020 - Add X-Content-Type-Options: nosniff support to Firefox
