CVE-2021-43816 HIGH

CVE-2021-43816: Improper Preservation of Permissions in containerd

Vendor Containerd
Product containerd
Weakness CWE-281
Published January 5, 2022
Last update April 22, 2025

CVSS base score

8.0/10
Attack vector Network
Attack complexity High
Privileges required High
User interaction None
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

What the vulnerability does

01Description

containerd is an open source container runtime. On installations using SELinux, such as EL8 (CentOS, RHEL), Fedora, or SUSE MicroOS, with containerd since v1.5.0-beta.0 as the backing container runtime interface (CRI), an unprivileged pod scheduled to the node may bind mount, via hostPath volume, any privileged, regular file on disk for complete read/write access (sans delete). Such is achieved by placing the in-container location of the hostPath volume mount at either `/etc/hosts`, `/etc/hostname`, or `/etc/resolv.conf`. These locations are being relabeled indiscriminately to match the container process-label which effectively elevates permissions for savvy containers that would not normally be able to access privileged host files. This issue has been resolved in version 1.5.9. Users are advised to upgrade as soon as possible.

Key dates

02Disclosure timeline

January 5, 2022 CVE published
April 22, 2025 Record updated