An issue existed in the handling of snapshots. The issue was resolved with improved permissions logic. This issue is fixed in macOS Big Sur 11.0.1. A malicious application may be able to preview files it does not have access to.
https://support.apple.com/en-us/HT211931
http://seclists.org/fulldisclosure/2020/Dec/32
Source: Mitre, NVD
Published: 2020-12-08
Updated: 2021-07-21
Base Score: 4.3
Vector: CVSS2#AV:N/AC:M/Au:N/C:P/I:N/A:N
Severity: Medium
Base Score: 5.5
Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N