diff --git a/packages/google-cloud-containeranalysis/setup.py b/packages/google-cloud-containeranalysis/setup.py
index 590b56916dea..c61753a674fd 100644
--- a/packages/google-cloud-containeranalysis/setup.py
+++ b/packages/google-cloud-containeranalysis/setup.py
@@ -28,7 +28,7 @@
     "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.*",
     "grpc-google-iam-v1 >= 0.12.4, <1.0.0dev",
     "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",
     "grafeas >=1.4.1, <2.0dev",
 ]
 extras = {"libcst": "libcst >= 0.2.5"}
diff --git a/packages/google-cloud-containeranalysis/testing/constraints-3.7.txt b/packages/google-cloud-containeranalysis/testing/constraints-3.7.txt
index 3e38ec7fd1c7..f2ff391f2295 100644
--- a/packages/google-cloud-containeranalysis/testing/constraints-3.7.txt
+++ b/packages/google-cloud-containeranalysis/testing/constraints-3.7.txt
@@ -10,5 +10,5 @@ grpc-google-iam-v1==0.12.4
 proto-plus==1.22.0
 libcst==0.2.5
 grafeas==1.4.1
-protobuf==3.20.2
+protobuf==3.19.5