A tampering vulnerability exists when Microsoft browsers do not properly validate input under specific conditions. An attacker who exploited the vulnerability could pass custom command line parameters. In a web-based attack scenario, an attacker could host a specially crafted website designed to appear as a legitimate website to the user. However, the attacker would have no way to force the user to visit the specially crafted website. The attacker would have to convince the user to visit the specially crafted website, typically by way of enticement in an email or instant message. The security update addresses the vulnerability by correcting how Microsoft browsers validate input.