An array indexing vulnerability in the netfilter ipset subsystem in Linux, which can be exploited in some systems because of its nature to increment/decrement pointers out-of-bound.

The root cause of the vulnerability is a missing IP_SET_HASH_WITH_NET0 macro in `ip_set_hash_netportnet`, which leads it to use the wrong wrong `CIDR_POS(c)` macro for calulating array offsets.

This provides attackers with the primitive to arbitrarily increment/decrement a memory out-of-bound, which is likely
exploitable, attackers can manipulate a buffer pointer to obtain OOB read/write primitive; or increase the length of a buffer, to read/write out of bound.

https://seclists.org/oss-sec/2023/q3/216
https://git.kernel.org/linus/050d91c03b28ca479df13dfb02bcd2c60dd6a878