Microsoft patch can lock users out of Web sites

A recent Microsoft Corp. security patch for Internet Explorer (IE) can lock users out of certain Web sites and Microsoft’s own MSN e-mail service, Microsoft said late Wednesday.

The issue affects the cumulative patch for IE versions 5.01, 5.5 and 6.0 released on Feb. 5 and rated “critical” by Microsoft. The software maker released a software fix to correct the bug, according to the revised MS03-004 security bulletin at

Users, primarily consumers, were unable to access certain Web sites requiring user authentication after installing the patch, Microsoft said. This issue in itself does not present a new security vulnerability and the original patch does fix all the vulnerabilities it is meant to, the Redmond, Wash., vendor said.

Only users having trouble authenticating to Web sites or accessing MSN e-mail need to install the new fix, which is available on Microsoft’s security Web site, the vendor said.

The cumulative patch announced in MS03-004 includes all previously released patches for Microsoft’s Internet browser and fixes two newly discovered vulnerabilities involving IE’s cross-domain security model, which keeps windows of different domains from sharing information. In the worst case, these two flaws could enable a Web site operator to load and run malicious code on a user’s system.