diff --git a/src/Microsoft.DotNet.Wpf/src/Shared/MS/Internal/SecurityHelper.cs b/src/Microsoft.DotNet.Wpf/src/Shared/MS/Internal/SecurityHelper.cs
index c30467978a08cd1db39c3b8bc532bfe6cb8dfcfa..49aba05cc78a33dc3d2dabc94e86048f2b55191f 100644
--- a/src/Microsoft.DotNet.Wpf/src/Shared/MS/Internal/SecurityHelper.cs
+++ b/src/Microsoft.DotNet.Wpf/src/Shared/MS/Internal/SecurityHelper.cs
@@ -353,60 +353,24 @@ internal static bool IsFullTrustCaller()
         /// path.
         ///</summary>
         ///<remarks>
-        /// This function exists solely as a an optimazation for the debugger scenario
+        /// In .NET Core 3.0+, always return true.
         ///</remarks>
-        /// <SecurityNote>
-        ///    Critical: This code extracts the permission set associated with an appdomain by elevating
-        ///    TreatAsSafe: The information is not exposed
-        /// </SecurityNote>
         [SecuritySafeCritical]
         internal static bool CallerHasPermissionWithAppDomainOptimization(params IPermission[] permissionsToCheck)
         {
-#if NETFX
-            // in case of passing null return true
-            if (permissionsToCheck == null)
-                return true;
-            PermissionSet psToCheck = new PermissionSet(PermissionState.None);
-            for ( int i = 0 ; i < permissionsToCheck.Length ; i++ )
-            {
-                psToCheck.AddPermission(permissionsToCheck[i]);
-            }
-            PermissionSet permissionSetAppDomain = AppDomain.CurrentDomain.PermissionSet;
-            if (psToCheck.IsSubsetOf(permissionSetAppDomain))
-            {
-                return true;
-            }
-            return false;
-#else
             return true;
-#endif
         }
 
         /// <summary> Enables an efficient check for a specific permisison in the AppDomain's permission grant
         /// without having to catch a SecurityException in the case the permission is not granted.
         /// <summary>
-        /// <SecurityNote>
-        /// Caveat: This is not a generally valid substitute for doing a full Demand. The main cases not
-        /// covered are:
-        ///   1) call from PT AppDomain into full-trust one;
-        ///   2) captured PT callstack (via ExecutionContext) from another thread or context. Our Dispatcher
-        ///     does this.
-        ///
-        /// Critical: Accesses the Critical AppDomain.PermissionSet, which might contain sensitive information
-        ///     such as file paths.
-        /// Safe: Does not expose the permission object to the caller.
-        /// </SecurityNote>
+        /// <remarks>
+        /// In .NET Core 3.0+, always return true
+        /// </remarks>
         [SecuritySafeCritical]
         internal static bool AppDomainHasPermission(IPermission permissionToCheck)
         {
-#if NETFX
-            Invariant.Assert(permissionToCheck != null);
-            PermissionSet psToCheck = new PermissionSet(PermissionState.None);
-            psToCheck.AddPermission(permissionToCheck);
-            return psToCheck.IsSubsetOf(AppDomain.CurrentDomain.PermissionSet);
-#else
             return true;
-#endif
         }
 
         /// <SecurityNote>
@@ -560,11 +524,8 @@ internal static void DemandFilePathDiscoveryWriteRead()
         [SecurityCritical]
         internal static PermissionSet ExtractAppDomainPermissionSetMinusSiteOfOrigin()
         {
-#if NETFX
-            PermissionSet permissionSetAppDomain = AppDomain.CurrentDomain.PermissionSet;
-#else
+            // In .NET Core 3.0+, always use PermissionState.Unrestricted
             PermissionSet permissionSetAppDomain = new PermissionSet(PermissionState.Unrestricted);
-#endif
 
             // Ensure we remove the FileIO read permission to site of origin.
             // We choose to use unrestricted here because it does not matter