A security feature bypass vulnerability exists in Microsoft Edge when the Edge Content Security Policy (CSP) fails to properly validate certain specially crafted documents. An attacker who exploited the bypass could trick a user into loading a page containing malicious content. To exploit the bypass, an attacker must trick a user into either loading a page containing malicious content or visiting a malicious website. The attacker could also inject the malicious page into either a compromised website or an advertisement network. The security update addresses the bypass by correcting how the Edge CSP validates documents.