How to Check and Mitigate CVE-2026-98432 (Linux Kernel TCP Use-After-Free) on Ubuntu
On 27 October Anthropic published an exploit chain that gets a root shell on a Linux server across the network, with no credentials and no clicks. The bug behind it is CVE-2026-98432, a use-after-free in the IPv4 TCP handshake. The kernel’s own CVE team scores it 9.8. Ubuntu has no fixed kernel yet. I run an Ubuntu 22.04 VM in a colo that hosts a UniFi Network controller in Docker. When this landed I wanted three answers: is the box vulnerable, can I reduce the risk before Canonical ships a kernel, and has anything already been at it? This post is what I checked, what the first-party sources actually say, and the mitigations I tested. ...