There are two vulnerabilities here.
replyThe RxRPC one is definitely a different root cause (although caused by a very similar mistake).
For the ESP one it's a bit harder to tell. I don't think the wrong thing was fixed, just that there was a very similar bug in almost the same spot. Could be wrong about that though.
(you probably wrote this while I was editing my post.)
replyIt's absolutely the same issue in authencesn/ESP. There's another one in RxRPC that is AIUI completely unrelated.