> I believe it's the same on Debian based

"sysctl -a | grep net.mptcp.enabled" gives "net.mptcp.enabled = 1" on Debian 13 (Trixie). That's a non-server desktop install fwiw.

Edit - security advisory is here: (dated Oct 16) https://lists.debian.org/debian-security-announce/2026/msg00...