We found results for “”
CVE-2020-16120
Good to know:
Date: February 10, 2021
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.
Language: C
Severity Score
Related Resources (16)
Severity Score
Weakness Type (CWE)
Improper Privilege Management
CWE-269Top Fix
CVSS v3.1
Base Score: |
|
---|---|
Attack Vector (AV): | LOCAL |
Attack Complexity (AC): | LOW |
Privileges Required (PR): | HIGH |
User Interaction (UI): | NONE |
Scope (S): | UNCHANGED |
Confidentiality (C): | HIGH |
Integrity (I): | NONE |
Availability (A): | NONE |
CVSS v2
Base Score: |
|
---|---|
Access Vector (AV): | LOCAL |
Access Complexity (AC): | LOW |
Authentication (AU): | NONE |
Confidentiality (C): | PARTIAL |
Integrity (I): | NONE |
Availability (A): | NONE |
Additional information: |