In the Linux kernel, the following vulnerability has been resolved:

sctp: fix race between sctp_wait_for_connect and peeloff

sctp_wait_for_connect() drops and re-acquires the socket lock while
waiting for the association to reach ESTABLISHED state. During this
window, another thread can peeloff the association to a new socket via
getsockopt(SCTP_SOCKOPT_PEELOFF), changing asoc->base.sk. After
re-acquiring the old socket lock, sctp_wait_for_connect() returns
success without noticing the migration — the caller then accesses
the association under the wrong lock in sctp_datamsg_from_user().

Add the same sk != asoc->base.sk check that sctp_wait_for_sndbuf()
already has, returning an error if the association was migrated while
we slept.