The strike on December 5th is likely to be a big one, and I expect that CDG will be impacted (ground staff, air traffic control). Also, there's no reason to believe the strike will only last one day.
I would avoid CDG on the 5th and the following days. Actually, I had a flight to CDG on the 6th and one from CDG on the 7th, I changed my plans to avoid CDG, and the French Airspace all together!
Article in French:
https://www.lemonde.fr/societe/artic...0144_3224.html