diff --git a/Apps/Python-flask-xxe/vulnserver/src/requirements.txt b/Apps/Python-flask-xxe/vulnserver/src/requirements.txt
index c48c30d..ef901aa 100644
--- a/Apps/Python-flask-xxe/vulnserver/src/requirements.txt
+++ b/Apps/Python-flask-xxe/vulnserver/src/requirements.txt
@@ -1,3 +1,3 @@
 flask
-lxml
+lxml==4.9.4
 pycrypto