微软基线安全分析器(英语：Microsoft Baseline Security Analyzer ，简称MBSA)是微软为旗下的操作系统而设的保安辅助系统，透过找寻电脑系统上未有安装的安全更新及未达标之设置来评估系统的保安状况。受检查的部件除了有Windows本身的系统文件以外，还包括有：Internet Explorer, IIS web server, and products Microsoft SQL Server, and Microsoft Office macro settings等各部件。 现时最新的版本是2.2。

Microsoft Baseline Security Analyzer (MBSA) is a software tool released by Microsoft to determine security state by assessing missing security updates and less-secure security settings within Microsoft Windows, Windows components such as Internet Explorer, IIS web server, and products Microsoft SQL Server, and Microsoft Office macro settings. Security updates are determined by the current version of MBSA using the Windows Update Agent present on Windows computers since Windows 2000 Service Pack 3. The less-secure settings, often called Vulnerability Assessment (VA) checks, are assessed based on a hard-coded set of registry and file checks. An example of a VA might be that permissions for one of the directories in the /www/root folder of IIS could be set at too low a level, allowing unwanted modification of files from outsiders.