diff --git a/src/Dev/FixFolderPermissionsHelper.php b/src/Dev/FixFolderPermissionsHelper.php
new file mode 100644
index 00000000..7d1895c9
--- /dev/null
+++ b/src/Dev/FixFolderPermissionsHelper.php
@@ -0,0 +1,41 @@
+<?php
+
+namespace SilverStripe\Dev\Tasks;
+
+use SilverStripe\Assets\File;
+use SilverStripe\Assets\Folder;
+use SilverStripe\Core\Injector\Injectable;
+use SilverStripe\ORM\DB;
+use SilverStripe\ORM\Queries\SQLUpdate;
+use SilverStripe\Security\InheritedPermissionFlusher;
+
+/**
+ * Files imported from SS3 might end up with broken permissions if there is a case conflict.
+ * @see https://github.com/silverstripe/silverstripe-secureassets
+ * This helper class resets the `CanViewType` of files that are `NULL`.
+ * You need to flush your cache after running this via CLI.
+ */
+class FixFolderPermissionsHelper
+{
+    use Injectable;
+
+    /**
+     * @return int Returns the number of records updated.
+     */
+    public function run()
+    {
+        SQLUpdate::create()
+            ->setTable('"' . File::singleton()->baseTable() . '"')
+            ->setAssignments(['"CanViewType"' => 'Inherit'])
+            ->setWhere([
+                '"CanViewType" IS NULL',
+                '"ClassName"' => Folder::class
+            ])
+            ->execute();
+
+        // This part won't work if run from the CLI, because Apache and the CLI don't share the same cache.
+        InheritedPermissionFlusher::flush();
+
+        return DB::affected_rows();
+    }
+}
diff --git a/tests/php/Dev/Tasks/FixFolderPermissionsHelperTest.php b/tests/php/Dev/Tasks/FixFolderPermissionsHelperTest.php
new file mode 100644
index 00000000..341a50bc
--- /dev/null
+++ b/tests/php/Dev/Tasks/FixFolderPermissionsHelperTest.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace SilverStripe\Assets\Tests\Dev\Tasks;
+
+use SilverStripe\Assets\Folder;
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Dev\Tasks\FixFolderPermissionsHelper;
+
+/**
+ * Ensures that files with invalid permissions can be fixed.
+ */
+class FixFolderPermissionsHelperTest extends SapphireTest
+{
+    protected static $fixture_file = 'FixFolderPermissionsHelperTest.yml';
+
+    public function testTask()
+    {
+        $task = new FixFolderPermissionsHelper();
+        $updated = $task->run();
+
+        $this->assertEquals('Inherit', Folder::get()->filter('Name', 'ParentFolder')->first()->CanViewType);
+        $this->assertEquals('Anyone', Folder::get()->filter('Name', 'SubFolder')->first()->CanViewType);
+        $this->assertEquals('Inherit', Folder::get()->filter('Name', 'AnotherFolder')->first()->CanViewType);
+        $this->assertEquals(2, $updated);
+    }
+}
diff --git a/tests/php/Dev/Tasks/FixFolderPermissionsHelperTest.yml b/tests/php/Dev/Tasks/FixFolderPermissionsHelperTest.yml
new file mode 100644
index 00000000..401328fa
--- /dev/null
+++ b/tests/php/Dev/Tasks/FixFolderPermissionsHelperTest.yml
@@ -0,0 +1,11 @@
+SilverStripe\Assets\Folder:
+  parent:
+    Name: ParentFolder
+    CanViewType: NULL
+  subfolder:
+    Name: SubFolder
+    Parent: =>SilverStripe\Assets\Folder.parent
+    CanViewType: Anyone
+  anotherfolder:
+    Name: AnotherFolder
+    CanViewType: