SB2026052778 - Link following in crun

Description

This security bulletin contains information about 1 vulnerability.

1) Link following (CVE-ID: CVE-2026-47766)

CWE-ID: CWE-59 - Improper Link Resolution Before File Access ('Link Following')

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to create device nodes and symlinks outside the container rootfs.

The vulnerability exists due to improper link resolution in create_missing_devs() in src/libcrun/linux.c when processing an OCI bundle whose rootfs/dev is a symlink and /dev is not mounted. A local user can supply a crafted bundle to create device nodes and symlinks outside the container rootfs.

A pre-existing file named ptmx at the symlink target can be replaced with a pts/ptmx symlink before crun returns failure.

Remediation

Install update from vendor's website.

References

• https://github.com/containers/crun/security/advisories/GHSA-7vwr-4279-7gq5
• https://github.com/containers/crun