PT-2025-45670 · Crates.Io · Youki

Published 2025-11-05 · Updated 2025-11-05

OSV

CVSS v3.1

10

Critical

Base vector

AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Impact

youki utilizes bind mounting the container's /dev/null as a file mask. When performing this operation, the initial validation of the source /dev/null was insufficient. Specifically, we initially failed to verify whether /dev/null was genuinely present. However, we did perform validation to ensure that the /dev/null path existed within the container, including checking for symbolic links. Additionally, there was a vulnerability in the timing between validation and the actual mount operation.

As a result, by replacing /dev/null with a symbolic link, we can bind-mount arbitrary files from the host system.

This is a different project, but the core logic is similar to the CVE in runc. Issues were identified in runc, and verification was also conducted in youki to confirm the problems. https://github.com/opencontainers/runc/security/advisories/GHSA-9493-h29p-rfm2

Credits

Thanks to Lei Wang (@ssst0n3 from Huawei) for finding and reporting the original runc's vulnerability (Attack 1), and Li Fubang (@lifubang from acmcoder.com, CIIC) for discovering another attack vector in runc (Attack 2) based on @ssst0n3's initial findings.

Also, @cyphar helped youki in finding the problem.

Fix

Weakness Enumeration

CWE-61

CWE-363

Related Identifiers

GHSA-4G74-7CFF-XCV8

Affected Products

Youki

References · 6

• https://nvd.nist.gov/vuln/detail/CVE-2025-62161 · Security Note
• https://osv.dev/vulnerability/GHSA-4g74-7cff-xcv8 · Vendor Advisory
• https://github.com/opencontainers/runc/security/advisories/GHSA-9493-h29p-rfm2 · Note
• https://github.com/youki-dev/youki · Note
• https://github.com/youki-dev/youki/security/advisories/GHSA-4g74-7cff-xcv8 · Note
• https://github.com/youki-dev/youki/commit/5886c91073b9be748bd8d5aed49c4a820548030a · Note