diff --git a/packages/google-cloud-beyondcorp-clientgateways/setup.py b/packages/google-cloud-beyondcorp-clientgateways/setup.py
index 632d9eff2af8..8e3e995f15ab 100644
--- a/packages/google-cloud-beyondcorp-clientgateways/setup.py
+++ b/packages/google-cloud-beyondcorp-clientgateways/setup.py
@@ -26,7 +26,7 @@
 dependencies = [
     "google-api-core[grpc] >= 1.32.0, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.*,!=2.4.*,!=2.5.*,!=2.6.*,!=2.7.*",
     "proto-plus >= 1.22.0, <2.0.0dev",
-    "protobuf >= 3.20.2, <5.0.0dev",
+    "protobuf>=3.19.5,<5.0.0dev,!=3.20.0,!=3.20.1,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
     "grpc-google-iam-v1 >=0.12.4, <1.0.0dev",
 ]
 url = "https://github.com/googleapis/python-beyondcorp-clientgateways"
diff --git a/packages/google-cloud-beyondcorp-clientgateways/testing/constraints-3.7.txt b/packages/google-cloud-beyondcorp-clientgateways/testing/constraints-3.7.txt
index f6f583b9ae4b..b0cdb69d3d13 100644
--- a/packages/google-cloud-beyondcorp-clientgateways/testing/constraints-3.7.txt
+++ b/packages/google-cloud-beyondcorp-clientgateways/testing/constraints-3.7.txt
@@ -6,5 +6,5 @@
 # Then this file should have google-cloud-foo==1.14.0
 google-api-core==1.32.0
 proto-plus==1.22.0
-protobuf==3.20.2
+protobuf==3.19.5
 grpc-google-iam-v1==0.12.4