First of all – what does zero-day mean? It is the day a vulnerability was found. If a bug was around for 10 days it would be a 10-day vulnerability. Usually a fix will be developed in the form of a patch or workaround.
A zero-day exploit means an attack takes place the day a vulnerability is discovered.
On March 30, 2019, two zero-day vulnerabilities were discovered in Microsoft EDGE and Internet Explorer. Without getting too technical, the behind the scenes code of the browser can occur when you visit a malicious site and some of the same origin policy code allows other sites to intervene. When working correctly, it would prevent other sites from accessing your information.
Another vulnerability is related to MHT files. Internet Explorer can still read MHT files. If you are using Outlook, you may see this above an email: “If there are problems with how this message is displayed, click here to view it in a web browser.” It will then open in IE even if you are using Windows 10 with Edge. If the MHT file is infected you will have problems.
To prevent programs from opening IE, you can go into “Programs and Features” in Control Panel and then to “Turn Windows features on or off” and uncheck Internet Explorer 11. Restart your computer.