Cannabis products and CBD oil on a plane
Check the product under US federal rules
For a departure from the US, TSA lists medical marijuana with special instructions. Marijuana and some cannabis products, including some CBD oils, remain prohibited under federal law unless they contain no more than 0.3% THC on a dry-weight basis or are FDA-approved. A state medical card alone does not establish either exception. If screening reveals a suspected violation, TSA refers it to law enforcement.
CBD oil at the checkpoint
Confirm the composition and federal status of the actual product before considering its bottle size. A qualifying CBD oil is still a liquid: an ordinary carry-on container must be no larger than 3.4 oz/100 ml and fit in the quart-sized liquids bag. Medically necessary liquids may have separate screening conditions; see the liquids guide and medical travel guide.
Check every border on the route
The US screening rule does not decide whether a product may enter another country or pass through a transit point. Check the laws of each jurisdiction before travel. Putting cannabis or CBD oil in checked baggage does not remove a legal restriction.
Source: TSA: medical marijuana and CBD products.