diff --git a/core/api/test-current.txt b/core/api/test-current.txt
index c285e017571e8..f951df15ca5b4 100644
--- a/core/api/test-current.txt
+++ b/core/api/test-current.txt
@@ -2852,6 +2852,7 @@ package android.view {
     method @Nullable public final android.os.IBinder getWindowContextToken();
     method public final void setWindowContextToken(@NonNull android.os.IBinder);
     field public static final int ACCESSIBILITY_TITLE_CHANGED = 33554432; // 0x2000000
+    field public static final int FLAG_SLIPPERY = 536870912; // 0x20000000
     field public static final int PRIVATE_FLAG_NO_MOVE_ANIMATION = 64; // 0x40
     field public CharSequence accessibilityTitle;
     field public int privateFlags;
diff --git a/core/java/android/view/WindowManager.java b/core/java/android/view/WindowManager.java
index 9b3550477aaa0..47546848dcf3c 100644
--- a/core/java/android/view/WindowManager.java
+++ b/core/java/android/view/WindowManager.java
@@ -2105,6 +2105,7 @@ public interface WindowManager extends ViewManager {
          * {@hide}
          */
         @UnsupportedAppUsage
+        @TestApi
         public static final int FLAG_SLIPPERY = 0x20000000;
 
         /**
diff --git a/services/core/java/com/android/server/wm/DisplayPolicy.java b/services/core/java/com/android/server/wm/DisplayPolicy.java
index 801182c5beef0..1647eba19206d 100644
--- a/services/core/java/com/android/server/wm/DisplayPolicy.java
+++ b/services/core/java/com/android/server/wm/DisplayPolicy.java
@@ -54,6 +54,7 @@ import static android.view.WindowManager.LayoutParams.FLAG_LAYOUT_INSET_DECOR;
 import static android.view.WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;
 import static android.view.WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS;
 import static android.view.WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE;
+import static android.view.WindowManager.LayoutParams.FLAG_SLIPPERY;
 import static android.view.WindowManager.LayoutParams.LAYOUT_IN_DISPLAY_CUTOUT_MODE_ALWAYS;
 import static android.view.WindowManager.LayoutParams.LAYOUT_IN_DISPLAY_CUTOUT_MODE_DEFAULT;
 import static android.view.WindowManager.LayoutParams.LAYOUT_IN_DISPLAY_CUTOUT_MODE_SHORT_EDGES;
@@ -871,6 +872,20 @@ public class DisplayPolicy {
                 == PackageManager.PERMISSION_GRANTED;
     }
 
+    /**
+     * Only trusted overlays are allowed to use FLAG_SLIPPERY.
+     */
+    static int sanitizeFlagSlippery(int flags, int privateFlags, String name) {
+        if ((flags & FLAG_SLIPPERY) == 0) {
+            return flags;
+        }
+        if ((privateFlags & PRIVATE_FLAG_TRUSTED_OVERLAY) != 0) {
+            return flags;
+        }
+        Slog.w(TAG, "Removing FLAG_SLIPPERY for non-trusted overlay " + name);
+        return flags & ~FLAG_SLIPPERY;
+    }
+
     /**
      * Sanitize the layout parameters coming from a client.  Allows the policy
      * to do things like ensure that windows of a specific type can't take
@@ -951,6 +966,8 @@ public class DisplayPolicy {
         if (mExtraNavBarAlt == win) {
             mExtraNavBarAltPosition = getAltBarPosition(attrs);
         }
+
+        attrs.flags = sanitizeFlagSlippery(attrs.flags, attrs.privateFlags, win.getName());
     }
 
     /**
diff --git a/services/core/java/com/android/server/wm/WindowManagerService.java b/services/core/java/com/android/server/wm/WindowManagerService.java
index 498c00831fd27..ba4e429e1ed1b 100644
--- a/services/core/java/com/android/server/wm/WindowManagerService.java
+++ b/services/core/java/com/android/server/wm/WindowManagerService.java
@@ -57,6 +57,7 @@ import static android.view.WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
 import static android.view.WindowManager.LayoutParams.FLAG_SECURE;
 import static android.view.WindowManager.LayoutParams.FLAG_SHOW_WALLPAPER;
 import static android.view.WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED;
+import static android.view.WindowManager.LayoutParams.FLAG_SLIPPERY;
 import static android.view.WindowManager.LayoutParams.INPUT_FEATURE_NO_INPUT_CHANNEL;
 import static android.view.WindowManager.LayoutParams.INVALID_WINDOW_TYPE;
 import static android.view.WindowManager.LayoutParams.LAST_APPLICATION_WINDOW;
@@ -8270,8 +8271,10 @@ public class WindowManagerService extends IWindowManager.Stub
         h.token = channelToken;
         h.name = name;
 
+        flags = DisplayPolicy.sanitizeFlagSlippery(flags, privateFlags, name);
+
         final int sanitizedFlags = flags & (LayoutParams.FLAG_NOT_TOUCHABLE
-                | LayoutParams.FLAG_SLIPPERY | LayoutParams.FLAG_NOT_FOCUSABLE);
+                | FLAG_SLIPPERY | LayoutParams.FLAG_NOT_FOCUSABLE);
         h.layoutParamsFlags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL | sanitizedFlags;
         h.layoutParamsType = type;
         h.dispatchingTimeoutMillis = DEFAULT_DISPATCHING_TIMEOUT_MILLIS;