As part of Microsoft's scheduled April update cycle, a number of critical severity vulnerabilities were addressed in Microsoft Exchange. We have no information to suggest that these vulnerabilities are being used in active exploitation. However, given the recent focus on Exchange, we recommend the installation of updates as soon as practicable, as attackers may seek to build exploit capability which could be used against systems before the updates are applied.
The vulnerabilities affect Microsoft Exchange Server. The affected versions are:
- Exchange Server 2013
- Exchange Server 2016
- Exchange Server 2019
Organisations running an out-of-support version of Microsoft Exchange should update to a supported version without delay.
Exchange Online customers are already protected.
Recommendation