There's nothing written about it on the internet. Nothing about if it's currently possible to carry out, or how to counter it. Just this definition copy pasta everywhere:
STP (Spanning-Tree Protocol) mangling refers to the technique used for the attacker host to be elected as the new root bridge of the spanning tree. The attacker may start either by forging BPDUs (Bridge Protocol Data Units) with high priority assuming to be the new root, or by broadcasting STP Configuration/Topology Change Acknowledgement BPDUs to get his host elected as the new root bridge. By taking over the root bridge, the attacker will be able to intercept most of the traffic.
Also another question, what's a Configuration/Topology Change Acknowledgement BPDU?