criticallivepatched
day · Aug 18, 2026
PwnEscape: Linux networking guest-to-host escape (CVE-2026-99999)
› Linux kernel networking (host side of KVM/Firecracker and similar)
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Updates on Aug 18, 2026
Vercel Sandbox challenge opens.
## summary
Paulos Yibelo / pwn.ai found a Critical Linux networking flaw (CVE-2026-99999, CVSS 9.3) during Vercel’s $1M Sandbox challenge. Guest-controlled checksum metadata can rewrite an IPv4 header after validation, enabling host-memory disclosure and, in lab conditions, guest-to-host code execution on KVM/Firecracker. Upstream fix merged Oct 2026; host kernels need patch + reboot. Affects multi-tenant VPS / sandbox providers more than end-user desktops.
read the full incident →
