dotnet6.0/SOURCES/msbuild-no-systemsecurity.patch

--- a/src/Shared/ExceptionHandling.cs
+++ b/src/Shared/ExceptionHandling.cs
@@ -153,7 +153,9 @@ namespace Microsoft.Build.Shared
         internal static bool IsXmlException(Exception e)
         {
             return e is XmlException
+#if FEATURE_SECURITY_PERMISSIONS
                 || e is XmlSyntaxException
+#endif
                 || e is XmlSchemaException
                 || e is UriFormatException; // XmlTextReader for example uses this under the covers
         }