A new vulnerability has been found in Microsoft\u2019s Excel spreadsheet program, just a few days after the company fixed problems with several of its applications in its monthly patch distribution.One customer reported an attack using the vulnerability, which comes from an e-mail with a malicious Excel document attached, wrote Mike Reavey, Microsoft security program manager, on the company\u2019s security blog. The blog post did not give further details on what the malware does when downloaded. The blog post can be found here.Reavey noted that the e-mail application should prompt users to take care if they attempt to open the attachment. He cautioned against opening unsolicited documents, whomever they come from.Microsoft has updated its own Windows Live Safety Center, a Web-based antivirus and performance-improvement service now in beta release, to detect documents attempting to exploit the vulnerability, and also shared the information with security partners, Reavey wrote."We\u2019ve got the Office team engaged, of course, and they are hard at work investigating the vulnerability," Reavey wrote.On Tuesday, Microsoft issued 12 updates for 21 vulnerabilities, one of the company\u2019s largest patch handouts for applications including Internet Explorer, Outlook Express, Word, PowerPoint and Windows Media Player.Observers noted the patches affected mostly client-side applications. Of the 21 vulnerabilities, 19 could have allowed a hacker to gain remote control over a computer and possibly corrupt or steal data. \u2014 Jeremy Kirk, IDG News Service (London Bureau)Related Links:\n\nBill Gates to Leave Day-To-Day Role in 2008\n\nIs Microsoft\u2019s Size a Benefit or Burden?\n\nA Win for Microsoft in Massachusetts?This article is posted on our Microsoft Informer page. For more news on the Redmond, Wash.-based powerhouse, keep checking in.Check out our CIO News Alerts and Tech Informer pages for more updated news coverage.