Why ask? There has never been a release of Linux without a known local privilege escalation bug. If you take the union of all known exploits, they cover the entire history of Linux. Knowing the interval of this flaw is pointless.
Because I'm curious as to when the affected code was introduced and if it affected older kernels that I run. Pure curiosity, mainly, as I know chances are it will have been patched. I still have PTSD from the Spectre kernel fun, so cut me some slack ;)
