Check offset

src/Protocols/Http/Request.php

@@ -535,6 +535,9 @@ class Request
     {
         $file = [];
         $boundary = "\r\n$boundary";
+        if (\strlen($this->_buffer) < $section_start_offset) {
+            return 0;
+        }
         $section_end_offset = \strpos($this->_buffer, $boundary, $section_start_offset);
         if (!$section_end_offset) {
             return 0;