In one of the largest security updates since moving to a monthly patch release cycle, Microsoft Tuesday issued 12 bulletins detailing fixes for 21 separate vulnerabilities in a wide range of products.

Eight of the bulletins and 12 of the vulnerabilities were rated "critical" by the company. Three bulletins detailed fixes for "important" flaws, while one described a flaw of moderate severity. The vulnerabilities disclosed Tuesday affect several Microsoft products, including Internet Explorer (IE), Windows Media Player, Microsoft Outlook and PowerPoint.

Tuesday's announcement is "certainly one that people need to sit up and take notice of," said Michael Sutton, director of VeriSign's iDefense Labs. He also noted that most of the critical flaws disclosed Tuesday are on the client side, highlighting a continuing trend away from server-side security issues.

"Client-side vulnerabilities have become one of the most prominent methods by which computers become infected today," Oliver Friedrichs, director of Symantec's security response group, said in a statement. "Today's release continues that trend" and highlights the danger users face simply by visiting certain Web sites, he said.

One of the bulletins rated as critical by Microsoft described a cumulative upgrade for Internet Explorer that fixed eight newly discovered flaws in the company's Web browser. The impact of the flaws included remote code execution, information disclosure and user spoofing, according to Microsoft.

Another bulletin offers a fix for a critical vulnerability in how Windows handles the ART image format used by America Online Inc.'s client software. An attacker could exploit the flaw by creating a specially crafted ART image that would allow for remote-code execution on a victim's computer.

Another critical remote-code execution vulnerability disclosed Tuesday involves Microsoft Windows Media Player technology. The buffer-overflow flaw exists in the way Media Player handles the Portable Network Graphics (PNG) image format associated with Media Player and could allow an attacker to take complete control of an affected system, the company warned.

In addition, security administrators should pay particular attention to vulnerabilities detailed in bulletin MS06-25 and MS06-29, according to an advisory from McAfee..

For more enterprise computing news, visit Computerworld. Story copyright Computerworld, Inc.

Whitepapers

• Selecting Effective Virtual Directories
• A Modern Approach to On-Demand Email and Data Security
• Best Practices for HP Servers and HP Enterprise Virtual Array in a Microsoft Exchange
• Compliance, Protection, Recovery: A Layered Approach to Laptop Security
• Endpoint Security: Data Protection for IT, Freedom for Laptop Users
• IT Departments on Data Security: A Research Concepts Survey

View more SECURITY whitepapers

Webcasts

• Key Considerations for a Successful 802.11n Deployment
• Solutions to the Toughest IT Challenges in Remote Offices
• Lowering the Cost of Email Archives
• High Availability for SQL Server 2005 Using Array-Based Replication and Host-Based Mirroring Technologies
• Technical Overview of Exchange Server 2007 with HP Servers and Storage
• Bringing Order and Security to your Mobile Workforce: Corporate Mobility Policy and Device Management On-Demand

View more SECURITY webcasts

Special Reports

• The Evolution of Network Security
• Taking Virtualization Up a Notch
• Learn how to Keep your Mobile Workforce Connected
• The self-managed network

View more SECURITY special reports