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How the CVE Works
The vulnerability occurs when `/proc` or `/sys` in the container’s root filesystem (rootfs) are symbolic links. Normally, these directories should be virtual filesystems mounted by the kernel, but if they are symlinks, an attacker can manipulate them to escape the container and access the host’s root filesystem. Youki fails to enforce this security check, allowing container creation even when these directories are symlinks, unlike runc, which blocks such scenarios. This oversight could lead to full host compromise if exploited.
DailyCVE Form
Platform: Youki
Version:
Vulnerability: Symlink Escape
Severity: Critical
Date: Aug 14, 2025
Prediction: Patch by Sep 2025
What Undercode Say
Check for symlinks in rootfs ls -ld /proc /sys Mitigation command (manual) unlink /proc && mkdir /proc
How Exploit
- Attacker prepares a malicious rootfs with `/proc` or `/sys` as symlinks.
- Container is created using Youki, bypassing symlink checks.
3. Attacker accesses host filesystem via symlinked paths.
Protection from this CVE
- Update Youki to patched version.
- Enforce symlink checks in container runtime.
- Use `runc` as alternative.
Impact
- Host filesystem compromise.
- Privilege escalation.
- Container breakout.
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Sources:
Reported By: github.com
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