Of Tuesday's four updates, called "bulletins" by Microsoft, only one was labeled "critical" -- the most-serious rating in the company's four-step scoring system -- while the other three were marked "important," the next-most-dangerous category.

The 22 individual bugs patched today were more than in most odd-numbered months, which are typically light months for Microsoft. July's total was bested only by April's 64 and June's 34, and was tied with February's.

The standout bulletin was clearly the sole critical update, , researchers said today.

"It's quirky, and it's remotely exploitable," said Andrew Storms, director of security operations for nCircle Security, of the Vista and Windows update that plugs a hole in the operating systems' Bluetooth stack.

"It's at the top of our priority list," echoed Amol Sarwate, manager of Qualys' vulnerability research lab. "It could be exploited against someone using a Bluetooth mouse or headset, perhaps in a coffee shop, so it's tremendously important that people apply the patch, or if they can't do that, disable Bluetooth [on Vista and Windows 7]."