Source: https://code.google.com/p/google-security-research/issues/detail?id=458

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The attached testcase crashes Win 7 with Special Pool on win32k while accessing freed memory in bGetRealizedBrush​​.
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Proof of Concept:
https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/38277.zip