PowerShell · TravisEz13 · May 7, 2018 · May 4, 2018 · May 4, 2018 · May 7, 2018
@@ -108,6 +108,9 @@ private PowerShellAssemblyLoadContext(string basePaths)
         //  - Value: strong name of the TPA that contains the type represented by Key.
         private readonly Dictionary<string, string> _coreClrTypeCatalog;
         private readonly Lazy<HashSet<string>> _availableDotNetAssemblyNames;
+        private readonly HashSet<string> _blackListedAssemblies = new HashSet<string>(StringComparer.OrdinalIgnoreCase){
+                "System.Windows.Forms"
+            };
 
 #if !UNIX
         private string _winDir;
@@ -295,6 +298,13 @@ private Assembly Resolve(AssemblyLoadContext loadContext, AssemblyName assemblyN
         private bool TryFindInGAC(AssemblyName assemblyName, out string assemblyFilePath)
         {
             assemblyFilePath = null;
+            if (_blackListedAssemblies.Contains(assemblyName.Name))
+            {
+                // DotNet catches and throws a new exception with no inner exception
+                // We cannot change the message DotNet returns.
+                return false;
+            }
+
             if (Internal.InternalTestHooks.DisableGACLoading)
             {
                 return false;

@@ -1,5 +1,6 @@
 # Copyright (c) Microsoft Corporation. All rights reserved.
 # Licensed under the MIT License.
+
 Describe "Assembly.LoadFrom Validation Test" -Tags "CI" {
     BeforeAll {
         $ConsumerCode = @'

@@ -0,0 +1,34 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+Describe "Assembly::LoadWithPartialName Validation Test" -Tags "CI" {
+
+    $defaultErrorId = 'FileLoadException'
+    $testcases = @(
+        # verify winforms is blocked
+        @{
+            Name = 'system.windows.forms'
+            ErrorId = $defaultErrorId
+        }
+        # Verify alternative casing is blocked
+        @{
+            Name = 'System.Windows.Forms'
+            ErrorId = $defaultErrorId
+        }
+    )
+
+    # All existing cases should fail on all platforms either because it doesn't exist or
+    # because the assembly is blacklisted
+    It "Assembly::LoadWithPartialName should fail to load blacklisted assembly: <Name>" -TestCases $testcases {
+        param(
+            [Parameter(Mandatory)]
+            [string]
+            $Name,
+            [Parameter(Mandatory)]
+            [string]
+            $ErrorId
+        )
+
+        {[System.Reflection.Assembly]::LoadWithPartialName($Name)} | Should -Throw -ErrorId $ErrorId
+    }
+}