The Exchange Server flaw is one of 55 vulnerabilities fixed in Microsoft's Patch Tuesday update.
Microsoft issued a fix for a use-after-free Windows vulnerability that was being leveraged in attacks, as part of its October Patch Tuesday roundup.
Microsoft's June Patch Tuesday includes fixes for six vulnerabilities that have been used in attacks in the wild.
Overall, Microsoft patched 55 flaws, including four critical-severity remote code execution bugs.
Microsoft has released patches for a Windows bug that is being exploited in the wild and for four new Exchange vulnerabilities.