CVE-2026-47243
CriticalCVSS 9.2Summary
Kata Containers prior to version 3.31.0 is vulnerable to a guest-root to host-root escape in the standalone virtio-fs path. In this configuration, the host virtiofsd runs as root with --sandbox none --seccomp none, allowing an attacker with root access in the guest to bypass the guest virtio-fs client and submit raw FUSE requests to the host virtiofsd, creating symlinks in sensitive host locations such as /etc/cron.d, leading to host code execution as root.
Risk Assessment
An attacker with guest root privileges can gain full control of the host, breaking Kata Containers isolation.
Recommendation
Upgrade Kata Containers to version 3.31.0 or later, which includes the fix.
Original NVD description (English source)
Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. Prior to 3.31.0, the runtime-rs standalone virtio-fs path is vulnerable to a guest-root to host-root escape. In this configuration, Kata runs the host virtiofsd as root with --sandbox none --seccomp none, so an attacker with root-equivalent access inside the guest can bypass the guest virtio-fs client entirely by taking over the virtio-fs PCI device and building a virtqueue in userspace to submit raw FUSE requests directly to the host virtiofsd. A crafted FUSE_SYMLINK request whose new symlink name is an absolute host path is honored outside the configured shared directory, allowing guest root to create root-owned symlinks in sensitive host locations such as /etc/cron.d. By pointing such a symlink at a guest-controlled crontab payload reachable through a live runtime process's mount namespace, the attacker causes the host cron daemon to execute that payload as host root, crossing the Kata isolation boundary. This issue is fixed in version 3.31.0.