Linux kernel flaw lets guest workloads read host memory

A newly disclosed Linux kernel networking flaw lets code inside a virtual machine read its host's memory, The Hacker News reported. Vercel confirmed that a researcher demonstrated the leak against its production cloud sandboxes during a security challenge. Tracked as CVE-2026-99999, the flaw also enabled host crashes and administrator control on the researcher's own machines. Those results were laboratory demonstrations, and Vercel said no challenge report showed access to customer files, secrets or application data. A kernel patch adds checks on packet checksum data and has been backported to stable branches. Its author describes it as a partial defense. Operators must update and reboot the host kernel; updating a guest alone does not fix the host.