Updated: A new critical vulnerability impacting Exchange Server is being exploited in the wild.

Microsoft also is advising customers who rely on the on-premises version of Exchange to move to the 2019 version as soon as possible. Microsoft will support Exchange Server until October 14, 2025.

For Exchange Server SE, Microsoft explained, in addition to purchasing the required Server licenses and CALs, customers must also maintain an active subscription.

The Exchange Server Subscription Edition is now generally available. On Tuesday, Microsoft released the successor to the last locally installable Exchange Server 2019.