The Exchange product group released the February 2026 Security Updates for Exchange Server SE, Exchange 2019, and Exchange 2016. There were no updates released in January, so if you missed those, you didn’t. The SE SU is available to the public. Security updates for Exchange 2019 and Exchange 2016 will be available to organizations enrolled in the Extended Security Update program.
The vulnerabilities addressed in these Security Updates for Exchange Server are:
The Security Updates for each supported Exchange Server build are linked below:
Notes
- Security updates are Cumulative Update level specific. You cannot apply the Exchange 2019 CU15 update to Exchange 2019 CU14. When downloading, the security update might carry the same name for different Cumulative Updates. Nowadays, Microsoft adds the KB article number as a reference, but I would still tag the file name with the CU level for archival purposes, e.g., Exchange2019-CU15-KBxxxxxxx-x64-en.exe.
- Like Cumulative Updates, Security Updates are cumulative, and you only need to install the latest SU for your CU.
- Suppose you have deployed Exchange Management Tools to manage your on-premises Exchange Servers or installed the tools after removing the Last Exchange Server for recipient management. In that case, it is recommended that you apply the Security Update.
On a final note, as with any patch or update, it is recommended that you test it in a test environment before deploying it to production. However, it is not recommended to wait for regular maintenance cycles for security updates; a more agile approach is preferable, and the ratings indicate the level of urgency.