CVE-2021-38209: Observable Discrepancy

net/netfilter/nfconntrackstandalone.c in the Linux kernel before 5.12.2 allows observation of changes in any net namespace because these changes are leaked into all other net namespaces. This is related to the NFSYSCTLCTMAX, NFSYSCTLCTEXPECTMAX, and NFSYSCTLCTBUCKETS sysctls...