A critical cloud security vulnerability rated 10/10 has been reported for Microsoft users, along with persistent denial of service attacks affecting Windows and warnings about password theft. A new tool called Defendnot has been released, which can disable Windows Defender, Microsoft's antivirus protection. Developed by a security researcher known as es3n1n, Defendnot simplifies the process of bypassing Windows Defender by tricking it into disabling itself. It uses undocumented application programming interfaces (APIs) to convince Windows Defender that another antivirus solution is present, without relying on third-party antivirus code. The availability of Defendnot poses a significant risk, potentially aiding malicious actors.