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 win a race condition.

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
10.0.17763.8755 — https://support.microsoft.com/help/5087538
10.0.20348.5139 — https://support.microsoft.com/help/5087545
10.0.20348.5074 — https://support.microsoft.com/help/5087424
10.0.19044.7291 — https://support.microsoft.com/help/5087544
10.0.19045.7417 — https://support.microsoft.com/help/5094127
10.0.26100.32860 — https://support.microsoft.com/help/5087539
10.0.26100.32772 — https://support.microsoft.com/help/5087423
10.0.26200.8457 — https://support.microsoft.com/help/5089549
10.0.26200.8390 — https://support.microsoft.com/help/5089466
10.0.22631.7079 — https://support.microsoft.com/help/5087420
10.0.22631.7219 — https://support.microsoft.com/help/5093998
10.0.25398.2330 — https://support.microsoft.com/help/5087541
10.0.28000.2113 — https://support.microsoft.com/help/5089548
10.0.14393.9140 — https://support.microsoft.com/help/5087537
6.2.9200.26079 — https://support.microsoft.com/help/5087470
6.3.9600.23181 — https://support.microsoft.com/help/5087471