&gt;  I don&#x27;t know what problems you are talking about (I don&#x27;t have any)<p>the glaring security holes opened by them month after month? The HN link you&#x27;re posting a comment to is about the 5th bad exploit in third-party AV this year alone.<p>So far nothing seems to have been found in the MS built-in one.<p>Installing third-party AV means that you expose yourself to targeted attacks and, if this goes on like it currently does, to drive-by attacks too as by now malware authors must have gotten the hint that searching for vulnerabilities in those various AV products is a very worthwile effort.<p>In general, AV products provide a HUGE attack surface: They don&#x27;t just need to support natively many more file formats than any other piece of software, they also have to harden their support against exploit code purposefully written to be malicious.<p>And compared to many exploitable user-space applications, these AV products normally run in kernel-space, so an attacker doesn&#x27;t just gain remote code execution, they gain remote code execution with admin privileges.