Executive Summary

Informations
Name CVE-2020-16120 First vendor Publication 2021-02-10
Vendor Cve Last vendor Modification 2021-02-18

Security-Database Scoring CVSS v3

Cvss vector : CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
Overall CVSS Score 4.4
Base Score 4.4 Environmental Score 4.4
impact SubScore 3.6 Temporal Score 4.4
Exploitabality Sub Score 0.8
 
Attack Vector Local Attack Complexity Low
Privileges Required High User Interaction None
Scope Unchanged Confidentiality Impact High
Integrity Impact None Availability Impact None
Calculate full CVSS 3.0 Vectors scores

Security-Database Scoring CVSS v2

Cvss vector : (AV:L/AC:L/Au:N/C:P/I:N/A:N)
Cvss Base Score 2.1 Attack Range Local
Cvss Impact Score 2.9 Attack Complexity Low
Cvss Expoit Score 3.9 Authentication None Required
Calculate full CVSS 2.0 Vectors scores

Detail

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.

Original Source

Url : http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-16120

CWE : Common Weakness Enumeration

% Id Name
100 % CWE-269 Improper Privilege Management

CPE : Common Platform Enumeration

TypeDescriptionCount
Os 4
Os 3364

Sources (Detail)

Source Url
CONFIRM 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://www.openwall.com/lists/oss-security/2020/10/14/2
UBUNTU 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

Alert History

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0
1
2
Date Informations
2021-03-27 01:33:39
  • Multiple Updates
2021-02-18 21:23:22
  • Multiple Updates
2021-02-11 00:22:50
  • First insertion