Critical Linux Kernel Vulnerability PwnEscape Allows VM-to-Host Memory Read

A newly disclosed critical flaw in the Linux kernel allows code inside a virtual machine to read memory on the host computer it runs on. The vulnerability, tracked as CVE-2026-99999 and nicknamed PwnEscape, resides in the Linux kernel's networking code and is not tied to a specific cloud provider's configuration, meaning it can affect Linux-based virtual machines across various hypervisor setups.

Security researcher Karan Saini demonstrated the exploit against Vercel's live cloud sandboxes, and Vercel confirmed the issue. The demonstration confirmed that code running inside a guest VM can read arbitrary host memory, potentially exposing sensitive data such as credentials, secrets, and other virtual machines' data residing on shared infrastructure.

The Linux kernel maintainers have been notified, and a patch is expected in an upcoming kernel release. Vercel has stated it is applying mitigations. The vulnerability class allows privilege escalation from within a VM and cross-VM memory leakage on shared cloud infrastructure.