diff --git a/Chapter-4/activity_1/requirements.txt b/Chapter-4/activity_1/requirements.txt
index 424e5fb..3c32fb3 100644
--- a/Chapter-4/activity_1/requirements.txt
+++ b/Chapter-4/activity_1/requirements.txt
@@ -13,7 +13,7 @@ enum34==1.1.6
 Flask==0.12.2
 Flask-API==1.0
 Flask-Caching==1.3.3
-Flask-Cors==3.0.3
+Flask-Cors==3.0.9
 Flask-Testing==0.7.1
 graphviz==0.8.1
 h5py==2.7.1