Microsoft continued its policy of releasing monthly security updates with three new software patches on Tuesday, including fixes for the MSN Messenger instant messaging program, Windows Media Services and the Outlook e-mail client.

Microsoft publish three security bulletins, MS04-008, 009 and 010. Only one of the security holes, in Outlook, could allow attackers to run malicious code on affected computers, and none of the new vulnerabilities was rated "critical" by Microsoft, the company said.

The company released a patch for Microsoft Office XP Service Pack 2 and Microsoft Outlook 2002 Service Pack 2, MS04-009, that fixes a problem with the way Outlook handles URLs (uniform resource locators) that use the "mailto" tag. That tag allows Web page authors to insert links on Web pages that launch Outlook or other e-mail clients.

A problem with the way Outlook interprets mailto URLs could allow an attacker to use a specially formatted mailto URL to gain access to files on an affected system or insert and run malicious computer code, and is rated "important", Microsoft said.

Computers would have to be running a vulnerable version of Outlook and have the "Outlook Today" home page as their default homepage with Outlook. "Outlook Today" is only the home page until an e-mail account is created, Microsoft said.

Two other software bulletins, MS04-008 and 010 were both rated "moderate."

A software patch detailed in MS04-010 addresses a security hole in MSN Messenger version 6.0 and 6.1 instant messaging program that could allow an attacker to secretly view information on a user's hard drive.

A problem with the way Messenger treats requests from transfer files between Messenger installations allows attackers to use a specially formatted request to browse the recipient's hard drive and read files without the recipient knowing, Microsoft said.

Finally, MS04-008 fixes a security vulnerability in Windows 2000 Server Service Packs 2, 3 and 4. A problem with the way Windows Media Station Service and Windows Media Monitor Service process TCP/IP (Transmission Control Protocol/Internet Protocol) connections could allow an attacker to send specially formatted TCP/IP packets that shut down either service.

Windows Media Services is a component of Windows 2000 Server that allows customers to manage and distribute Windows Media-format content over the Internet.

The vulnerability, which is of "moderate" seriousness, could make Windows 2000 Server installations vulnerable to a denial of service attack, Microsoft said.