CVE-2020-16120
- Source
- https://nvd.nist.gov/vuln/detail/CVE-2020-16120
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-16120.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2020-16120
- Related
- Published
- 2021-02-10T20:15:15Z
- Modified
- 2024-09-18T01:00:20Z
- Severity
-
- 4.4 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N CVSS Calculator
- Summary
- [none]
- Details
-
Overlayfs did not properly perform permission checking when copying up files in an overlayfs and could be exploited from within a user namespace, if, for example, unprivileged user namespaces were allowed. It was possible to have a file not readable by an unprivileged user to be copied to a mountpoint controlled by the user, like a removable device. This was introduced in kernel version 4.19 by commit d1d04ef ("ovl: stack file ops"). This was fixed in kernel version 5.8 by commits 56230d9 ("ovl: verify permissions in ovlpathopen()"), 48bd024 ("ovl: switch to mounter creds in readdir") and 05acefb ("ovl: check permission to open real file"). Additionally, commits 130fdbc ("ovl: pass correct flags for opening real directory") and 292f902 ("ovl: call secutiry hook in ovlrealioctl()") in kernel 5.8 might also be desired or necessary. These additional commits introduced a regression in overlay mounts within user namespaces which prevented access to files with ownership outside of the user namespace. This regression was mitigated by subsequent commit b6650da ("ovl: do not fail because of O_NOATIMEi") in kernel 5.11.
- References
-
- https://www.openwall.com/lists/oss-security/2020/10/14/2
- 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://security-tracker.debian.org/tracker/CVE-2020-16120
Affected packages
Debian:11 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source
Debian:12 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source
Debian:13 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source