CVE-2026-68137 net/x25: fix use-after-free in x25_kill_by_neigh()

In the Linux kernel, the following vulnerability has been resolved: net/x25: fix use-after-free in x25killbyneigh x25killbyneigh walks the global X.25 socket list looking for sockets attached to a terminating neighbour. x25listlock protects list membership while the lookup is in progress, but it...