
Previously, the record for most flaws patched was 49, in October of last year.
9 of the 17 bulletins are "critical," while the rest are "important." Critical is the highest threat level while 'important' is second highest.
One security analyst was very surprised by how high the number was (via CW):
We were expecting the larger release this month, based on the normal cadence. But a whopping 64 CVEs is out of line with anything normal for Microsoft. All hands on deck will be required next week.