Mozilla Firefox 80, Mozilla Firefox ESR 68.12, Mozilla Firefox ESR 78.2, Mozilla Thunderbird 68.12 and Mozilla Thunderbird 78.2 : By holding a reference to the eval() function from an about:blank window, a malicious webpage could have gained access to the InstallTrigger object which would allow them to prompt the user to install an extension. Combined with user confusion, this could result in an unintended or malicious extension being installed.