Microsoft has urged users to download patches to eliminate nine vulnerabilities.
Three problems in Office relate to Web services, the Office Web Components (OWC) 2000 and 2002, which allow documents to be worked on using a Web browser, indicating the problems that companies may face as they roll out their Internet-based systems.
Although Microsoft points out that two of these weaknesses would require intimate knowledge of a user's storage system, the third bug could provide a hacker with this information.
The other vulnerabilities would allow documents to be accessed, read or changed.
Microsoft advises that the patches be installed urgently but users of Office XP can install the newly released Service Pack 2. The faulty software is shipped with products using the 2000, 2002, 2003 and XP suffix.