As I understand it, Nikita Khrushchev made the decision to install missiles in Cuba more or less on his own. His colleagues on the Politburo were less than thrilled by the crisis and its resolution. As a result of this and other fiascos, Khrushchev was removed from power by a coup within the CCCP.
Could the same thing happen as a result of Putin’s foolhardy war against Ukraine? Not exactly, because Putin is not constrained by a party, an ideology, and a bureaucracy in the same way; he runs the whole show himself. The only hope would be that the military and the security apparatus would be sufficiently appalled to refuse to obey orders. That’s a big lift.
A Communist Party as a restraining force in history? It seems implausible at first, but it’s actually true. It is one of the big differences between Xi and Putin.