The qualities of CBD oil are no longer to be proven. Unfortunately, there are still some countries that consider it to be similar to THC, i.e. a psychoactive compound. It is therefore illegal to transport or consume products containing it on their territory. On the other hand, countries that recognize CBD for its therapeutic virtues authorize citizens and travellers to consume it.
Therefore, flying with CBD oil may be legal in some countries and illegal in others. The solution to avoid finding yourself in an illegal situation is to find out about the laws regarding CBD in the country of destination and also in the countries where you will be transiting.