Exploiters changing walkspeed

I know that the client has control over their speed, but can they also change other client’s walkspeeds?

by default, no. when the client “changes” their speed, the change in the property value doesn’t actually replicate to the server (you can test this in studio). the reason why they still go fast is because they have complete control over their character and the position of their character automatically gets replicated.

they can’t change the walkspeed of another client because that client has control over their own character. however, if your client-server model allows for an exploiter to abuse it (eg. you had a RemoteEvent with parameters playerName and setWalkspeed which allows client to tell the server to change their speed based on things the client chooses) then yes, an exploiter could change the walkspeed of another player