This can be dangerous for a number of reasons.
The most obvious reason being a danger with teeth, claws. A cat bite or scratch can kill a glider quickly due to the toxins they emit.
A less obvious reason involving cat feces would be toxoplasmosis. Rat or mouse feces could lead to tyzzer's disease. A widespread of diseases that could pass. Giardia in a cat may be harmful but giardia in a glider can be extremely deadly much faster simply because they are smaller.
Then there is the simple fact that marsupials simply do not do well if under a lot of stress. A predator in the same room as a glider would for sure stress a glider out. If a glider has a parasite that is dormant and is under a lot of stress the parasite can become active. Just like in humans stress does crazy things to the bodies.