UBUNTU-CVE-2026-31414: Ubuntu/linux vulnerability

In the Linux kernel, the following vulnerability has been resolved: netfilter: nfconntrackexpect: use expect->helper Use expect->helper in ctnetlink and /proc to dump the helper name. Using nfcthelp() without holding a reference to the master conntrack is unsafe. Use exp->master->helper in ctnetlink path if userspace does not provide an explicit helper when creating an expectation to retain the existing behaviour. The ctnetlink expectation path holds the reference on the master conntrack and nfconntrackexpect lock and the nfnetlink glue path refers to the master ct that is attached to the skb.