CVE-2026-47243: Kata Containers runtime-rs 3.30: virtiofsd symlink escape

[Aurelien Bombo <aurelien.bombo () microsoft com>]

This vulnerability was fixed in Kata Containers 3.31.0:

https://github.com/kata-containers/kata-containers/releases/tag/3.31.0
https://github.com/kata-containers/kata-containers/commit/555b7738fe2f699af6d57712cf75330f012b4e3b

Description:

In the runtime-rs standalone virtio-fs path, Kata Containers runs virtiofsd
as root with --sandbox none --seccomp none.

If an attacker has root-equivalent execution inside the Kata guest VM,
they can send raw FUSE requests directly to the host virtiofsd.

Then, a raw FUSE_SYMLINK request whose new symlink name is
an absolute host path is honored outside the virtio-fs shared directory.

This lets guest root create host-root-owned symlinks in sensitive host paths.

CVE: CVE-2026-47243
GHSA: GHSA-2gv2-cffp-j227

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

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Aurelien Bombo
Kata Containers Vulnerability Management Team