Adobe Flash is problematic software. It is software that tends to linger on computers unpatched and full of vulnerabilities, and so has become a common vector for malware and ransomware infections. A 4th zero day exploint in 4 months has been announced, which means more ways your computer can become compromised. In addition to the security problems, it is also a resource hog. This is the main reason Flash has never been allowed to run on Apple iOS devices.

Here is a comprehensive explainer, all you need to know.

So seriously, uninstall flash where possible. If you absolutely do need it, make sure it is set to install patches automatically.