CVE-2021-4120

Public Exploit
snapd could be made to bypass intended access restrictions through snap content interfaces and layout paths

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

Category

8.2
CVSS
Severity: High
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.10%
Vendor Advisory fedoraproject.org Vendor Advisory fedoraproject.org Vendor Advisory ubuntu.com
Affected: Canonical Ltd. snapd
Published at:
Updated at:

References

Link Tags
https://ubuntu.com/security/notices/USN-5292-1 patch vendor advisory
https://bugs.launchpad.net/snapd/+bug/1949368 issue tracking exploit third party advisory
http://www.openwall.com/lists/oss-security/2022/02/18/2 mailing list exploit third party advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3QTBN7LLZISXIA4KU4UKDR27Q5PXDS2U/ vendor advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XCGHG6LJAVJJ72TMART6A7N4Z6MSTGI7/ vendor advisory

Frequently Asked Questions

What is the severity of CVE-2021-4120?
CVE-2021-4120 has been scored as a high severity vulnerability.
How to fix CVE-2021-4120?
To fix CVE-2021-4120, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-4120 being actively exploited in the wild?
It is possible that CVE-2021-4120 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-4120?
CVE-2021-4120 affects Canonical Ltd. snapd.
This platform uses data from the NIST NVD, MITRE CVE, MITRE CWE, First.org and CISA KEV but is not endorsed or certified by these entities. CVE is a registred trademark of the MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. CWE is a registred trademark of the MITRE Corporation and the authoritative source of CWE content is MITRE's CWE web site.
© 2025 Under My Watch. All Rights Reserved.