diff --git a/docs/samples/custom/kfserving-custom-model/model-server/requirements.txt b/docs/samples/custom/kfserving-custom-model/model-server/requirements.txt
index 2bd6b74..fb6f7d2 100644
--- a/docs/samples/custom/kfserving-custom-model/model-server/requirements.txt
+++ b/docs/samples/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==7.0.0
-protobuf==3.11.3
+protobuf==3.18.3
 pyasn1==0.4.8
 pyasn1-modules==0.2.8
 pycparser==2.19
diff --git a/docs/samples/custom/kfserving-custom-model/requirements.txt b/docs/samples/custom/kfserving-custom-model/requirements.txt
index 33e0252..a594344 100644
--- a/docs/samples/custom/kfserving-custom-model/requirements.txt
+++ b/docs/samples/custom/kfserving-custom-model/requirements.txt
@@ -50,7 +50,7 @@ pexpect==4.8.0
 pickleshare==0.7.5
 prometheus-client==0.7.1
 prompt-toolkit==3.0.4
-protobuf==3.11.3
+protobuf==3.18.3
 ptyprocess==0.6.0
 pyasn1==0.4.8
 pyasn1-modules==0.2.8