CVE-2025-62596: youki container escape and denial of service due to arbitrary write gadgets and procfs write redirects

Vulnerability summary

CVE-2025-62596 is a critical (CVSS 10.0) UNIX Symbolic Link (Symlink) Following vulnerability in youki-dev youki. EPSS estimates a 0.27% chance of exploitation in the next 30 days, higher than 18.9% of scored vulnerabilities.

Timeline

1. 05-11-2025
   PublishedVulnerability first disclosed.
2. 06-11-2025
   Last modifiedVulnerability information updated.

Description

Youki is a container runtime written in Rust. In versions 0.5.6 and below, youki’s apparmor handling performs insufficiently strict write-target validation, and when combined with path substitution during pathname resolution, can allow writes to unintended procfs locations. While resolving a path component-by-component, a shared-mount race can substitute intermediate components and redirect the final target. This issue is fixed in version 0.5.7.

• CWE-61UNIX Symbolic Link (Symlink) FollowingThe 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.
• CWE-363Race Condition Enabling Link FollowingThe product checks the status of a file or directory before accessing it, which produces a race condition in which the file can be replaced with a link before the access is performed, causing the product to access the wrong file.