Apply correction for ticket #4392

Author: evilaliv3

backend/globaleaks/utils/securetempfile.py

@@ -19,7 +19,7 @@ def __init__(self, filesdir):
         """
         filename = str(uuid.uuid4())
         self.filepath = os.path.join(filesdir, filename)
-        self.cipher = Cipher(ChaCha20(os.urandom(32), os.urandom(16)), mode=None, backend=default_backend)
+        self.cipher = Cipher(ChaCha20(os.urandom(32), os.urandom(16)), mode=None, backend=default_backend())
 
     @property
     def size(self):