CVE-2021-4120: Input Validation
First published: Thu Feb 17 2022(Updated: )
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
Credit: security@ubuntu.com security@ubuntu.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Canonical snapd | <=2.54.2 | |
| Canonical Ubuntu Linux | =18.04 | |
| Canonical Ubuntu Linux | =20.04 | |
| Canonical Ubuntu Linux | =21.10 | |
| Fedoraproject Fedora | =34 | |
| Fedoraproject Fedora | =35 | |
| debian/snapd | <=2.37.4-1+deb10u1<=2.37.4-1+deb10u3 | 2.49-1+deb11u2 2.57.6-1 2.61.2-2 |
| ubuntu/snapd | <2.54.3+18.04 | 2.54.3+18.04 |
| ubuntu/snapd | <2.54.3+20.04 | 2.54.3+20.04 |
| ubuntu/snapd | <2.54.3+21.10.1 | 2.54.3+21.10.1 |
| ubuntu/snapd | <2.54.3+14.04~ | 2.54.3+14.04~ |
| ubuntu/snapd | <2.54.3 | 2.54.3 |
| ubuntu/snapd | <2.54.3+16.04~ | 2.54.3+16.04~ |
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Reference Links
- http://www.openwall.com/lists/oss-security/2022/02/18/2
- https://bugs.launchpad.net/snapd/+bug/1949368
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3QTBN7LLZISXIA4KU4UKDR27Q5PXDS2U/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XCGHG6LJAVJJ72TMART6A7N4Z6MSTGI7/
- https://ubuntu.com/security/notices/USN-5292-1
- https://launchpad.net/bugs/cve/CVE-2021-4120
- 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/
- https://www.openwall.com/lists/oss-security/2022/02/18/2
- https://security-tracker.debian.org/tracker/CVE-2021-4120
- https://github.com/snapcore/snapd/commit/f3f669d720ed8b0bcb73da7789843bf43b5c16cf
- https://www.cve.org/CVERecord?id=CVE-2021-4120
- https://nvd.nist.gov/vuln/detail/CVE-2021-4120
- https://ubuntu.com/security/CVE-2021-4120
Frequently Asked Questions
What is CVE-2021-4120?
CVE-2021-4120 is a vulnerability in snapd 2.54.2 that allows snaps to inject arbitrary AppArmor policy rules and escape strict snap confinement.
How severe is CVE-2021-4120?
CVE-2021-4120 has a severity rating of 7.8 (high).
Which versions of snapd are affected?
Version 2.54.2 of snapd is affected.
How can I fix CVE-2021-4120?
To fix CVE-2021-4120, update snapd to version 2.54.3 or higher.
Where can I find more information about CVE-2021-4120?
You can find more information about CVE-2021-4120 at the following references: [Link 1](http://www.openwall.com/lists/oss-security/2022/02/18/2), [Link 2](https://bugs.launchpad.net/snapd/+bug/1949368), [Link 3](https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3QTBN7LLZISXIA4KU4UKDR27Q5PXDS2U/).
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