Exactly so officially you can indeed only rely on what your distribution promises you. In practice you may, with varying success, assume that if you are using a

Exactly so officially you can indeed only rely on what your distribution promises you. In practice you may, with varying success, assume that if you are using a version that is LTS by one of the big distributions some fixes will land in mainline as well and therefore also in your distribution. Particularly for really critical fixes. Of course, only officially rely on whatever agreement you have with your distribution/distributor.