An issue was discovered in the Linux kernel before 5.11.11. The netfilter subsystem allows attackers to cause a denial of service (panic) because net/netfilter/x_tables.c and include/linux/netfilter/x_tables.h lack a full memory barrier upon the assignment of a new table value, aka CID-175e476b8cdf.
https://lists.debian.org/debian-lts-announce/2021/06/msg00020.html
https://lists.debian.org/debian-lts-announce/2021/06/msg00019.html
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.11