Each patch covers single or multiple vulnerabilities in one of the firm's software products. Microsoft issued 12 patches last month that covered a total of 21 vulnerabilities.
Windows is scheduled to receive four updates this month, at least one of which is rated 'critical'. Office is set for three updates, one of which is rated 'critical'.
Microsoft said that it will also issue one non-security high priority update, but did not provide any additional information.
The company releases security patches on the second Tuesday of every month. The pre-announcement is designed to give IT staff time to prepare for the upgrade.
- Microsoft Security Bulletin Advance Notification