CVE-2020-16120: Unprivileged overlay + shiftfs read access
First published: Tue Oct 13 2020(Updated: )
Last updated 29 November 2024
Credit: security@ubuntu.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | <5.11 | |
| Ubuntu Linux | =14.04 | |
| Ubuntu Linux | =16.04 | |
| Ubuntu Linux | =18.04 | |
| Ubuntu Linux | =20.04 | |
| debian/linux | 5.10.223-1 5.10.226-1 6.1.123-1 6.1.128-1 6.12.12-1 6.12.13-1 | |
| Ubuntu | =14.04 | |
| Ubuntu | =16.04 | |
| Ubuntu | =18.04 | |
| Ubuntu | =20.04 |
Remedy
disable unprivileged user namespaces if not needed via sudo sysctl kernel.unprivileged_userns_clone=0 do this permanently by adding kernel.unprivileged_userns_clone = 0 to /etc/sysctl.d/99-userns.conf
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Reference Links
- https://git.kernel.org/linus/05acefb4872dae89e772729efb194af754c877e8
- https://git.kernel.org/linus/48bd024b8a40d73ad6b086de2615738da0c7004f
- https://git.kernel.org/linus/56230d956739b9cb1cbde439d76227d77979a04d
- https://git.kernel.org/linus/b6650dab404c701d7fe08a108b746542a934da84
- https://git.kernel.org/linus/d1d04ef8572bc8c22265057bd3d5a79f223f8f52
- https://launchpad.net/bugs/1894980
- https://launchpad.net/bugs/1900141
- https://ubuntu.com/USN-4576-1
- https://ubuntu.com/USN-4577-1
- https://ubuntu.com/USN-4578-1
- https://www.openwall.com/lists/oss-security/2020/10/14/2
- https://launchpad.net/bugs/cve/CVE-2020-16120
- https://www.openwall.com/lists/oss-security/2020/10/13/6
- https://security-tracker.debian.org/tracker/CVE-2020-16120
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-16120
- https://nvd.nist.gov/vuln/detail/CVE-2020-16120
- https://ubuntu.com/security/CVE-2020-16120
Frequently Asked Questions
What is the severity of CVE-2020-16120?
CVE-2020-16120 has a severity rating that enables potential privilege escalation in systems using vulnerable versions of Overlayfs.
How do I fix CVE-2020-16120?
To fix CVE-2020-16120, update to the patched versions of Linux kernels: 5.10.223-1, 5.10.226-1, 6.1.123-1, 6.1.119-1, or 6.12.10-1.
Which systems are affected by CVE-2020-16120?
CVE-2020-16120 affects multiple Linux distributions including Debian and various versions of Ubuntu.
Can CVE-2020-16120 be exploited in user namespaces?
Yes, CVE-2020-16120 can be exploited from within a user namespace if unprivileged user namespaces are allowed.
What is Overlayfs in relation to CVE-2020-16120?
Overlayfs is a layered filesystem in Linux that is implicated in the permission-checking flaw described in CVE-2020-16120.
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