CVE-2020-16120 Affecting kernel-obs-build package, versions <4.12.14-150.63.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-SLES150-KERNELOBSBUILD-2697644
- published14 Apr 2022
- disclosed26 Nov 2020
Introduced: 26 Nov 2020
CVE-2020-16120 (opens in a new tab)How to fix?
Upgrade SLES:15.0 kernel-obs-build to version 4.12.14-150.63.1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-obs-build package and not the kernel-obs-build package as distributed by SLES.
See How to fix? for SLES:15.0 relevant fixed versions and status.
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 ovl_path_open()"), 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 ovl_real_ioctl()") 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.suse.com/security/cve/CVE-2020-16120.html
- https://bugzilla.suse.com/1177470
- 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