WebExtensions can bypass user prompts to first save and then open an arbitrarily downloaded file. This can result in an executable file running with local user privileges without explicit user consent. This vulnerability affects Firefox < 58.Referenceshttp://www.securitytracker.com/id/1040270https://bugzilla.mozilla.org/show_bug.cgi?id=1390882https://usn.ubuntu.com/3544-1/http://www.securityfocus.com/bid/102786https://www.mozilla.org/security/advisories/mfsa2018-02/
