I'm doing a project to my University that consist studiyng vulnerabilities on TOR network. One attack I came across on Intenet is the "replay attack". This type of attack allows a adversary, that controls Entry Node and some Extit node, duplicate cells to raise duplicate errores on Exit Node.
My question is simple (but I didn't finde info on Internet): is this attack still efective on TOR? or is there a patch that fixed it?