RAinUsTa
low
Currently, the concurrency of the gossip block validation is set at 4, see code snippet linked. There isn't a per peer rate limit, and the gossip queue is set to size 256. A very gossippy peer can flood the node and hog the 4 block validation spots by sending a variety of different block messages.
A healthy trust worth peer will only gossip message roughly once per block, but a malicious peer can choose to gossip continuously.
If a malicious peer broadcasts uniquely signed blocks (even if it is not signer) at a rate that exceeds the 4 concurrent block validation's throughput, then it will start clogging the message validation queue of 256, and other peer's messages would be missed.
The usual way to enforce fairness between peers is to have rate limiting so that no single peer can drown out / clog the validation queue.
When the validation queue is filled up, other good peer's messages will be ignored. Ideally, the messages are processed with fairness across peers.
Manual Review
Implement a per-peer rate limiter such that each peer is only allowed to broadcast N messages per second, and any additional messages beyond that is ignored as spam.