diff --git a/Tests/InputFilterTest.php b/Tests/InputFilterTest.php
index cda40c01..c003af12 100644
--- a/Tests/InputFilterTest.php
+++ b/Tests/InputFilterTest.php
@@ -508,6 +508,30 @@ public static function casesGeneric(): array
                 'C:\Documents\Newsletters\tmp',
                 'From generic cases',
             ],
+            'path with parent traversal segment' => [
+                'path',
+                'uploads/../config.php',
+                '',
+                'From generic cases',
+            ],
+            'path with leading parent traversal' => [
+                'path',
+                '../secret',
+                '',
+                'From generic cases',
+            ],
+            'path with trailing parent traversal' => [
+                'path',
+                'uploads/..',
+                '',
+                'From generic cases',
+            ],
+            'filename containing dots is kept' => [
+                'path',
+                'archive/backup..2018/file.txt',
+                'archive/backup..2018/file.txt',
+                'From generic cases',
+            ],
             'user_01' => [
                 'username',
                 '&<f>r%e\'d',
diff --git a/src/InputFilter.php b/src/InputFilter.php
index f8aedf61..f2395d2b 100644
--- a/src/InputFilter.php
+++ b/src/InputFilter.php
@@ -906,6 +906,12 @@ private function cleanHtml($source)
      */
     private function cleanPath($source)
     {
+        // Reject any parent-directory (`..`) segment. The patterns below otherwise let a
+        // single `..` through on Linux-style paths (e.g. images/../config.php).
+        if (preg_match('#(?:^|[\\\\/])\.\.(?:[\\\\/]|$)#', $source)) {
+            return '';
+        }
+
         $linuxPattern = '/^[A-Za-z0-9_\/-]+[A-Za-z0-9_\.-]*([\\\\\/]+[A-Za-z0-9_-]+[A-Za-z0-9_\.-]*)*$/';
 
         if (preg_match($linuxPattern, $source)) {