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Youki: If /proc and /sys in the rootfs are symbolic links, they can potentially be exploited to gain access to the host root filesystem.

High severity GitHub Reviewed Published Aug 14, 2025 in youki-dev/youki • Updated Aug 14, 2025

Package

cargo youki (Rust)

Affected versions

< 0.5.5

Patched versions

0.5.5

Description

Summary

If /proc and /sys in the rootfs are symbolic links, they can potentially be exploited to gain access to the host root filesystem.

Details

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.

Impact

The following advisory appears to be related to this vulnerability:

References

@utam0k utam0k published to youki-dev/youki Aug 14, 2025
Published by the National Vulnerability Database Aug 14, 2025
Published to the GitHub Advisory Database Aug 14, 2025
Reviewed Aug 14, 2025
Last updated Aug 14, 2025

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Local
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(5th percentile)

Weaknesses

UNIX Symbolic Link (Symlink) Following

The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files. Learn more on MITRE.

CVE ID

CVE-2025-54867

GHSA ID

GHSA-j26p-6wx7-f3pw

Source code

Credits

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