In security bulletin MS04-028, Microsoft urged users to update their systems.
Most older Microsoft products, including Windows NT 4.0, Internet Explorer 5.5, Windows Me and Windows 98 are unaffected. However, Windows XP, Windows 2003 and Office 2003 are among 24 products and service packs that contain the flaw.
By default, Windows 98, 98 SE, Me, NT 4.0, 2000, and XP Service Pack 2 are not vulnerable to this exploit. However, the vulnerable component could be installed on these operating systems. Microsoft advised users to install the appropriate security update for those applications.
Richard Brain, technical director at security consultancy Procheckup, said, "For such a widely used format, Microsoft should have done something far sooner." He said JPeg exploits have existed since 1994.
Microsoft said a hacker could not force users to visit a malicious website, but would attempt to persuade them to visit the site, typically by getting them to click a link.