In the Linux kernel, nft_nat netmap setup was only partially initializing an IPv4 address structure before copying it into a NAT range. The upper bytes were left uninitialized and later used by nf_nat_setup_info during NAT evaluation. This flaw is a CWE-908, resulting in uninitialized memory that could corrupt kernel structures and potentially cause a crash and service interruption. The flaw affects only the IPv4 path; the IPv6 mapping path correctly zero‑initializes the full 16 bytes.

All kernel releases that include the nft_nat netmap implementation before the commit restoring full initialization are vulnerable. Any distribution running such a kernel without the patch is at risk, regardless of kernel version number.

The CVSS score of 5.5 indicates moderate severity, and the EPSS score of less than 1 % suggests a low exploitation probability. The vulnerability is not listed in the CISA KEV catalog, implying no known public exploits yet. An attacker would need to send specially crafted packets that trigger the nft_nat netmap path, which is reachable via the host’s network interfaces. The impact could be a kernel panic, leading to denial of service.