Linux TCP use-after-free CVE-2026-98432 explained, CVSS 9.8

TCP Use-After-Free: CVE-2026-98432 / CVSS 9.8

A use-after-free flaw in the Linux IPv4 TCP handshake, CVE-2026-98432, carries a CVSS 3.1 score of 9.8 from the kernel CNA, and fixes have landed on several stable branches. Unpatched Linux 4.4 and later kernels are affected. As of 8:00 PM CDT on October 29, Ubuntu releases and RHEL 8, 9 and 10 had no fix, and a kernel update needs a host reboot to take effect.

Why it matters: It maps patch status per distribution and explains how to check the kernel, since updating container images does not replace patching and rebooting the host.