A flaw was found in the way RTAS handled memory accesses in userspace to kernel communication. On a locked down (usually due to Secure Boot) guest system running on top of PowerVM or KVM hypervisors (pseries platform) a root like local user could use this flaw to further increase their privileges to that of a running kernel.
https://bugzilla.redhat.com/show_bug.cgi?id=1900844
Source: MITRE
Published: 2020-12-15
Updated: 2020-12-22
Type: CWE-862
Base Score: 7.2
Vector: AV:L/AC:L/Au:N/C:C/I:C/A:C
Impact Score: 10
Exploitability Score: 3.9
Severity: HIGH
Base Score: 6.7
Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 0.8
Severity: MEDIUM