In the Linux kernel, the following vulnerability has been resolved: mptcp: ensure snduna is properly initialized on connect This is strictly related to commit fb7a0d334894 ("mptcp: ensure sndnxt is properly initialized on connect"). It turns out that syzkaller can trigger the retransmit after fallback and before processing any other incoming packet - so that snduna is still left uninitialized. Address the issue explicitly initializing snduna together with sndnxt and writeseq.