TL;DR A researcher published RustyTux, a working proof-of-concept for a Linux kernel privilege escalation flaw. It abuses an ESP-in-TCP use-after-free race in the strparser and espintcp code. Both the vulnerability details and the exploit code are now public. No exploitation in the wild has been confirmed. Why This Linux Kernel Privilege Escalation Matters The espintcp module ships in kernels from many major distributions.