diff --git a/src/recommendationservice/requirements.txt b/src/recommendationservice/requirements.txt
index 206a759..2ac824f 100644
--- a/src/recommendationservice/requirements.txt
+++ b/src/recommendationservice/requirements.txt
@@ -17,7 +17,7 @@ grpcio-tools==1.0.0
 httplib2==0.11.3
 idna==2.7
 opencensus==0.1.5
-protobuf==3.5.2.post1
+protobuf==3.18.3
 pyasn1==0.4.3
 pyasn1-modules==0.2.2
 pytz==2018.5