CVE-2026-23398

CVE-2026-23398 describes a NULL pointer dereference vulnerability in the Linux kernel's `icmp_tag_validation()` function. This flaw occurs when a system, configured for hardened PMTU discovery, receives a malformed ICMP Fragmentation Needed error packet containing an unregistered protocol number. Successful exploitation leads to a kernel panic, resulting in a Denial of Service (DoS) condition. The attack vector is network-based, requiring specific conditions and packet content, suggesting moderate complexity. There is currently no public exploit code available, no evidence of active exploitation, and community discussion and media coverage are minimal, with a very low EPSS score indicating a low likelihood of exploitation.