Still safe to use?

I'm still on the Android 6 008FW firmware, since Android 7 doesn't seem to be as stable for me. Is it still safe to use this firmware? I noticed in the settings that the security patch level is still on august 2016, so that means a lot of vulnerabilities are still present in this firmware. Now i'm a bit scared that i might get malware or something.

How (un)safe is it to use the Android 6 rom? I only just Kodi and some tv apps.