Merged main into live

Author: mijacobs

docs/msbuild/how-to-use-environment-variables-in-a-build.md

@@ -1,7 +1,7 @@
 ---
 title: 'Use Environment Variables in a Build'
 description: Work with environment variables in MSBuild project files, and use environment variables to set build options without modifying the project file.
-ms.date: 8/5/2025
+ms.date: 8/11/2025
 ms.topic: how-to
 helpviewer_keywords:
 - environment variables, referencing
@@ -16,6 +16,9 @@ ms.subservice: msbuild
 
 When you build projects, it's often necessary to set build options using information that isn't in the project file or the files that comprise your project. This information is typically stored in environment variables.
 
+> [!NOTE]
+> MSBuild treats environment variables as trusted inputs. They can cause MSBuild to load build logic such as tasks, `.targets`, or `.props` files from custom locations or alter how the build executes.
+
 ## Reference environment variables
 
  All environment variables that are valid MSBuild property names are available to the MSBuild project file as properties. Valid property names are described in [MSBuild properties](msbuild-properties.md). For example, environment variables that begin with a number aren't available in MSBuild.