Windows Win32k 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 chain other vulnerabilities in order to successfully gain unauthorized access to the target environment.

How could an attacker exploit this vulnerability?
An authenticated attacker could exploit this vulnerability by placing a specially crafted keyboard layout file on the affected system and chaining it with an additional vulnerability. Successful exploitation could allow the attacker to gain SYSTEM privileges. User interaction is not required.

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