If /proc and /sys in the rootfs are symbolic links, they can potentially be exploited to gain access to the host root filesystem.
For security reasons, container creation should be prohibited if /proc or /sys in the rootfs is a symbolic link.
I verified this behavior with youki.
When /proc or /sys is a symbolic link, runc fails to create the container, whereas youki successfully creates it.
This is the fix related to this issue in runc.
* https://github.com/opencontainers/runc/pull/3756
* https://github.com/opencontainers/runc/pull/3773
* https://github.com/opencontainers/runc/blob/main/libcontainer/rootfs_linux.go#L590
* https://github.com/opencontainers/runc/blob/main/tests/integration/mask.bats#L60
The following advisory appears to be related to this vulnerability: * https://github.com/advisories/GHSA-vpvm-3wq2-2wvm * https://github.com/advisories/GHSA-fh74-hm69-rqjw
{
"cwe_ids": [
"CWE-61"
],
"severity": "HIGH",
"github_reviewed_at": "2025-08-14T16:39:04Z",
"github_reviewed": true,
"nvd_published_at": "2025-08-14T16:15:39Z"
}