Security Update for Exchange Server SE RTM SU3 (KB5066366)

Supported Operating Systems

Windows Server 2019, Windows Server 2022, Windows Server 2025

Exchange Server Subscription Edition System Requirements and Prerequisites
For information about Exchange Subscription Edition system requirements and prerequisites, see the following topics:

• Exchange Subscription Edition System Requirements
• Exchange Subscription Edition Prerequisites

Actual requirements will vary based on system configuration. For more detailed system requirements, please refer to the Exchange Server Subscription Edition Technical Documentation Library.

We recommend that you restart your server before you install an update.

Then, follow these steps:

1. To start the download, select the Download button, and then do one of the following:
   • a. To start the installation immediately, temporarily disable any anti-virus software and then select Run.
   • b. To copy the download file to your computer for installation at a later time, select Save.
2. Temporarily disable any anti-virus software before starting the installation.
3. After the installation is completed, re-enable the antivirus software, and then restart your computer.
   (The installation program may prompt you to restart. We strongly recommend that you restart the computer even if you are not prompted to do this.)

If problems occur during or after the installation, please see Fix failed Exchange Server updates and run the Exchange Server Health Checker tool. Check Exchange Team Blog for latest news on updates. Microsoft Support is available for any persistent problems.

Exchange Server Subscription Edition File Hash Information

1. File Name: ExchangeSubscriptionEdition-KB5066366-x64-de.exe
   Language: German (de-de)
   SHA 256: 38F236809D7301C5271E2C46CC6917732BB4EEC854F5BD6B1D2432935C749AB4
2. File Name: ExchangeSubscriptionEdition-KB5066366-x64-en.exe
   Language: English (en-us)
   SHA 256: 2CFA1173FD4871D017B669A25A94FCE63A8D4C12B37DA9A163CE55AB7359C4EF
3. File Name: ExchangeSubscriptionEdition-KB5066366-x64-es.exe
   Language: Spanish (es-es)
   SHA 256: 4583683FE5D1BE469855A5A29791DA4322BB2C7C5EC9DFBCE326D5FEB6A06125
4. File Name: ExchangeSubscriptionEdition-KB5066366-x64-fr.exe
   Language: French (fr-fr)
   SHA 256: 4B06EDF7DBD16E9F098FC52DDE625A0A45DF62499C066FFBB9CE7356AE4A5FC1
5. File Name: ExchangeSubscriptionEdition-KB5066366-x64-it.exe
   Language: Italian (it-it)
   SHA 256: F43CA006C6009D8DAA95D1D66AAB9E1F22918D61691CD84C9E3977ACCE733A77
6. File Name: ExchangeSubscriptionEdition-KB5066366-x64-ja.exe
   Language: Japanese (ja-jp)
   SHA 256: 5901919149093E59FA7002F130449F51D12DEF073A65F9D764353205BC7A2767
7. File Name: ExchangeSubscriptionEdition-KB5066366-x64-ko.exe
   Language: Korean (ko-kr)
   SHA 256: D9D8490DC76864CFAC73A0D899C3B0331FD7C7A6AEEAB7D0EBAAAC6655E54152
8. File Name: ExchangeSubscriptionEdition-KB5066366-x64-pt.exe
   Language: Portuguese-Brazil (pt-br)
   SHA 256: 372DA98D3438C9AE0EC38F6C3C25000D60D7616DE53B94496A851FBCF373C0CA
9. File Name: ExchangeSubscriptionEdition-KB5066366-x64-ru.exe
   Language: Russian (ru-ru)
   SHA 256: EEC63049222681E83754A713278851AF9659800F5C705034D47088FD1FA523FA
10. File Name: ExchangeSubscriptionEdition-KB5066366-x64-zh-hans.exe
    Language: Chinese-China (zh-cn)
    SHA 256: FAA9685A12F890CBC18C9A0DBDB1DECB075DDD373FD1058BAE8CC377CFE06222
11. File Name: ExchangeSubscriptionEdition-KB5066366-x64-zh-hant.exe
    Language: Chinese-Taiwan (zh-tw)
    SHA 256: 7CCC0C80E12FDF82BCE4157AF4FF5D4699F7E5D10525BAFB8B5EF76A79D585E3