An Ubuntu kernel bug causes container crashes

Oh I've known such people and even had to combat them because they were refusing to apply the mandatory fixes for a bug that was causing their firewall to leak memory like crazy and crash every two weeks or so. Instead they wanted to profit from a downtime caused by the crash to install more RAM and postpone the next crash! When insisting for applying fixes, to the question "but if it bugs?" I had to respond "in the worst case it will continue not to work".

But what you seem to be ignoring here is that the older the kernel, the harder it is to backport fixes, and the most likely they are to be wrong, particularly when taken out of the context of all other fixes that were surrounding the original patch. When I was a stable maintainer, I used to receive many messages like "do not take this patch without this one" or "I'll provide you a different one for this version as it's not sufficient" etc. The risk of getting a fix wrong when applying it yourself to a tree without the author's approval is quite high. Thus in addition to missing tons of fixes, the few you get (the so called "security fixes" that make vendors sell) are often bogus and are the ones that will take your system down.

Really, do not use EOL kernels.