Microsoft today said it will ship 13 security updates next week to patch 22 vulnerabilities in Internet Explorer, Windows, Visio and Visual Studio.
Next Tuesday's patch lineup is larger than July's on the update count, but matches that month's vulnerability total. That's unusual, since the company usually delivers a heavier load in even-numbered months.
"Twenty-two [vulnerabilities] is not a big month, it's more in the medium range, what with the larger numbers we've seen so far in 2011," said Andrew Storms, director of security operations at nCircle Security.
"Overall, it's what we could have expected, although as an 'up' month, the number [of vulnerabilities] isn't up to the usual," said Storms. "The number [of flaws] each month is increasing.... A new baseline is being drawn this year."
In June, for example, Microsoft issued 16 updates -- the company calls them "bulletins" -- that patched 34 bugs. Two months before that, Microsoft fixed 64 flaws with 17 bulletins.
Two of the 13 bulletins for this month's Patch Tuesday were rated "critical" by Microsoft, the highest threat ranking in its four-step system. Nine were pegged "important" and the remaining pair were labeled "moderate."
The usual bi-monthly update for Internet Explorer (IE) was one of the two judged critical, and will probably be the one that most experts recommend users deploy first, said Storms.
"The IE [update] is critical across the board," noted Storms, referring to the details that Microsoft posted in its monthly advance notification today. "True to form, it will be the one most say should be patched first because client-side bugs are the top priority and the most targeted."
All versions of IE will be patched next Tuesday, including the newest edition, IE9. At least some of the bugs -- Microsoft almost always fixes multiple flaws in each of the six browser security updates it does annually -- for each version will be pegged critical, meaning that they can be used by attackers to compromise a Windows PC.
Microsoft first patched IE9 in June, three months after its release, when the company plugged four critical holes in the browser.
The other critical update planned for next week is for the two newest versions of Microsoft's server software, Windows Server 2008 and Server 2008 R2. The eight-year-old Server 2003 is also affected, but Microsoft rated the update as important, not critical, for that edition.
As he as before, Storms today bemoaned the dearth of information that could be gleaned from the advance notice.
"It's a tea leaf month," Storms said. "It's like reading tea leaves. There's very little to go on and a lot of data at the same time. It's just difficult to read anything from what we have here."
What Microsoft marked as "Bulletin 3," however, did catch his eye. That bulletin will apply only to Windows 7 and Server 2008 R2, the two newest versions of Microsoft's client and server operating systems.
"The interesting bulletins are those that only affect the older software, or only affect the newer software," said Storms, noting that Bulletin 3 is in the second camp.
That update will be a puzzler until Microsoft ships its updates since Windows Vista and Server 2008 R2 share much of their code base with their respective follow-ons, Windows 7 and Server 2008: Typically, if one line needs to be patched, so does the other.
Of the nine updates Microsoft will deliver for Windows, five won't be necessary for Windows XP, the decade-old operating system that Microsoft is trying to shove into retirement as quickly as possible.
Also on next week's slate are an update for the .Net framework and Visual Studio 2005 development toolset, and another for Visio, the diagramming application that's part of the Office family.
Microsoft patched Visio 2003 last month to stymie DLL load hijacking attacks that rely on tricking applications or operating systems into loading a malicious file with the same name as a legitimate DLL, or dynamic link library.
This month, the company will patch all the other still-supported versions, including Visio 2003, 2007 and 2010. It's possible that the update will fix DLL load hijacking problems in those editions.
A month ago, Marcus Carey, a researcher with Rapid7, pointed out that the Visio 2003 bug might pique the interest of hackers active in targeted attacks because, "People who typically use Visio are high-value, often network or systems engineers [who] often have the keys to the [network] kingdom."
Storms agreed today. "It looks like Visio could be a new target," he said.
The 13 updates will be released at approximately 1 p.m. ET on Aug. 9.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His e-mail address is firstname.lastname@example.org.