Incorrect default permissions in Linux kernel - CVE-2019-15793
Published: April 24, 2020 / Updated: May 1, 2020
Vulnerability identifier: #VU95690
CSH Severity: Low
CVSSv4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2019-15793
CWE-ID: CWE-276
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerable software:
Linux kernel
Linux kernel
Software vendor:
Linux Foundation
Linux Foundation
Description
The vulnerability allows a local user to escalate privileges on the system.
In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, several locations which shift ids translate user/group ids before performing operations in the lower filesystem were translating them into init_user_ns, whereas they should have been translated into the s_user_ns for the lower filesystem. This resulted in using ids other than the intended ones in the lower fs, which likely did not map into the shifts s_user_ns. A local attacker could use this to possibly bypass discretionary access control permissions.
Remediation
Install update from vendor's repository.