diff --git a/docs/samples/v1alpha2/custom/kfserving-custom-model/model-server/requirements.txt b/docs/samples/v1alpha2/custom/kfserving-custom-model/model-server/requirements.txt
index a4308cfe0d..bdd853a743 100644
--- a/docs/samples/v1alpha2/custom/kfserving-custom-model/model-server/requirements.txt
+++ b/docs/samples/v1alpha2/custom/kfserving-custom-model/model-server/requirements.txt
@@ -21,7 +21,7 @@ minio==5.0.7
 numpy==1.18.1
 oauthlib==3.1.0
 Pillow==7.1.0
-protobuf==3.11.3
+protobuf==3.15.6
 pyasn1==0.4.8
 pyasn1-modules==0.2.8
 pycparser==2.19