Hello @Sophia
Welcome to Microsoft Q&A Platform:
ExchangeServer2016-x64-cu12.iso link below:
https://www.microsoft.com/en-us/download/details.aspx?id=57827
ExchangeServer2019-x64-CU12.ISO link below:
https://www.microsoft.com/en-us/download/details.aspx?id=104131
I hope this helps!
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