Windows Encrypting File System (EFS) Elevation of Privilege Vulnerability

According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?
Successful exploitation of this vulnerability requires an attacker to have a deep understanding of the system. Successful exploitation is not guaranteed and depends on a combination of factors that might include the environment, system configuration, and the presence of additional security measures.

What privileges could be gained by an attacker who successfully exploited this vulnerability?
An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.

Security updates
10.0.17763.9245 — https://support.microsoft.com/help/5122876
10.0.20348.5622 — https://support.microsoft.com/help/5122882
10.0.19044.7725 — https://support.microsoft.com/help/5122878
10.0.26100.33438 — https://support.microsoft.com/help/5122871
10.0.26200.9445 — https://support.microsoft.com/help/5124008
10.0.22631.7582 — https://support.microsoft.com/help/5122880
10.0.28000.2954 — https://support.microsoft.com/help/5124012
10.0.14393.9512 — https://support.microsoft.com/help/5123099
6.2.9200.26349 — https://support.microsoft.com/help/5123065
6.3.9600.23398 — https://support.microsoft.com/help/5123066