diff --git a/MODULE.bazel b/MODULE.bazel
index d2a5b08b..04574248 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -39,7 +39,7 @@ local_path_override(
     path = "modules/c",
 )
 
-bazel_dep(name = "protobuf", version = "27.1")
+bazel_dep(name = "protobuf", version = "27.3")
 
 # C++
 bazel_dep(name = "rules_proto_grpc_cpp", version = "0.0.0.rpg.version.placeholder")
diff --git a/modules/c/MODULE.bazel b/modules/c/MODULE.bazel
index 04e77ac0..51cc7be3 100644
--- a/modules/c/MODULE.bazel
+++ b/modules/c/MODULE.bazel
@@ -4,6 +4,6 @@ module(
     compatibility_level = 1,
 )
 
-bazel_dep(name = "protobuf", version = "27.1")
+bazel_dep(name = "protobuf", version = "27.3")
 bazel_dep(name = "rules_cc", version = "0.0.9")
 bazel_dep(name = "rules_proto_grpc", version = "0.0.0.rpg.version.placeholder")
diff --git a/modules/cpp/MODULE.bazel b/modules/cpp/MODULE.bazel
index b7cd6c2b..530fc7d4 100644
--- a/modules/cpp/MODULE.bazel
+++ b/modules/cpp/MODULE.bazel
@@ -5,6 +5,6 @@ module(
 )
 
 bazel_dep(name = "grpc", version = "1.65.0")
-bazel_dep(name = "protobuf", version = "27.1")
+bazel_dep(name = "protobuf", version = "27.3")
 bazel_dep(name = "rules_cc", version = "0.0.9")
 bazel_dep(name = "rules_proto_grpc", version = "0.0.0.rpg.version.placeholder")
diff --git a/modules/example_protos/MODULE.bazel b/modules/example_protos/MODULE.bazel
index ee653d26..430cb6e3 100644
--- a/modules/example_protos/MODULE.bazel
+++ b/modules/example_protos/MODULE.bazel
@@ -4,5 +4,5 @@ module(
     compatibility_level = 1,
 )
 
-bazel_dep(name = "protobuf", version = "27.1")
+bazel_dep(name = "protobuf", version = "27.3")
 bazel_dep(name = "rules_proto", version = "6.0.2")
diff --git a/modules/objc/MODULE.bazel b/modules/objc/MODULE.bazel
index e2dff946..a2bfa4fe 100644
--- a/modules/objc/MODULE.bazel
+++ b/modules/objc/MODULE.bazel
@@ -6,6 +6,6 @@ module(
 
 bazel_dep(name = "apple_support", version = "1.16.0")
 bazel_dep(name = "grpc", version = "1.65.0")
-bazel_dep(name = "protobuf", version = "27.1")
+bazel_dep(name = "protobuf", version = "27.3")
 bazel_dep(name = "rules_cc", version = "0.0.9")
 bazel_dep(name = "rules_proto_grpc", version = "0.0.0.rpg.version.placeholder")
diff --git a/modules/python/requirements.in b/modules/python/requirements.in
index 04c2a284..a931e9c0 100644
--- a/modules/python/requirements.in
+++ b/modules/python/requirements.in
@@ -1,3 +1,3 @@
 grpcio==1.65.4  # TODO: remove once pulling grpc from BCR @grpc works
 grpclib==0.4.7
-protobuf==5.27.2
+protobuf==5.28.0
diff --git a/modules/python/requirements.txt b/modules/python/requirements.txt
index 62560f8e..2c75681f 100644
--- a/modules/python/requirements.txt
+++ b/modules/python/requirements.txt
@@ -159,16 +159,16 @@ multidict==6.0.5 \
     --hash=sha256:fce28b3c8a81b6b36dfac9feb1de115bab619b3c13905b419ec71d03a3fc1423 \
     --hash=sha256:fe5d7785250541f7f5019ab9cba2c71169dc7d74d0f45253f8313f436458a4ef
     # via grpclib
-protobuf==5.27.2 \
-    --hash=sha256:0e341109c609749d501986b835f667c6e1e24531096cff9d34ae411595e26505 \
-    --hash=sha256:176c12b1f1c880bf7a76d9f7c75822b6a2bc3db2d28baa4d300e8ce4cde7409b \
-    --hash=sha256:354d84fac2b0d76062e9b3221f4abbbacdfd2a4d8af36bab0474f3a0bb30ab38 \
-    --hash=sha256:4fadd8d83e1992eed0248bc50a4a6361dc31bcccc84388c54c86e530b7f58863 \
-    --hash=sha256:54330f07e4949d09614707c48b06d1a22f8ffb5763c159efd5c0928326a91470 \
-    --hash=sha256:610e700f02469c4a997e58e328cac6f305f649826853813177e6290416e846c6 \
-    --hash=sha256:7fc3add9e6003e026da5fc9e59b131b8f22b428b991ccd53e2af8071687b4fce \
-    --hash=sha256:9e8f199bf7f97bd7ecebffcae45ebf9527603549b2b562df0fbc6d4d688f14ca \
-    --hash=sha256:a109916aaac42bff84702fb5187f3edadbc7c97fc2c99c5ff81dd15dcce0d1e5 \
-    --hash=sha256:b848dbe1d57ed7c191dfc4ea64b8b004a3f9ece4bf4d0d80a367b76df20bf36e \
-    --hash=sha256:f3ecdef226b9af856075f28227ff2c90ce3a594d092c39bee5513573f25e2714
+protobuf==5.28.0 \
+    --hash=sha256:018db9056b9d75eb93d12a9d35120f97a84d9a919bcab11ed56ad2d399d6e8dd \
+    --hash=sha256:510ed78cd0980f6d3218099e874714cdf0d8a95582e7b059b06cabad855ed0a0 \
+    --hash=sha256:532627e8fdd825cf8767a2d2b94d77e874d5ddb0adefb04b237f7cc296748681 \
+    --hash=sha256:6206afcb2d90181ae8722798dcb56dc76675ab67458ac24c0dd7d75d632ac9bd \
+    --hash=sha256:66c3edeedb774a3508ae70d87b3a19786445fe9a068dd3585e0cefa8a77b83d0 \
+    --hash=sha256:6d7cc9e60f976cf3e873acb9a40fed04afb5d224608ed5c1a105db4a3f09c5b6 \
+    --hash=sha256:853db610214e77ee817ecf0514e0d1d052dff7f63a0c157aa6eabae98db8a8de \
+    --hash=sha256:d001a73c8bc2bf5b5c1360d59dd7573744e163b3607fa92788b7f3d5fefbd9a5 \
+    --hash=sha256:dde74af0fa774fa98892209992295adbfb91da3fa98c8f67a88afe8f5a349add \
+    --hash=sha256:dde9fcaa24e7a9654f4baf2a55250b13a5ea701493d904c54069776b99a8216b \
+    --hash=sha256:eef7a8a2f4318e2cb2dee8666d26e58eaf437c14788f3a2911d0c3da40405ae8
     # via -r requirements.in
diff --git a/test_workspaces/common_cpp_library/MODULE.bazel b/test_workspaces/common_cpp_library/MODULE.bazel
index 68adb3fc..76fd6049 100644
--- a/test_workspaces/common_cpp_library/MODULE.bazel
+++ b/test_workspaces/common_cpp_library/MODULE.bazel
@@ -1,4 +1,4 @@
-bazel_dep(name = "protobuf", version = "27.1")
+bazel_dep(name = "protobuf", version = "27.3")
 bazel_dep(name = "rules_cc", version = "0.0.9")
 bazel_dep(name = "rules_proto", version = "6.0.2")
 bazel_dep(name = "rules_proto_grpc_cpp", version = "0.0.0.rpg.version.placeholder")
diff --git a/test_workspaces/exclusions/MODULE.bazel b/test_workspaces/exclusions/MODULE.bazel
index 7b849c66..815fa77c 100644
--- a/test_workspaces/exclusions/MODULE.bazel
+++ b/test_workspaces/exclusions/MODULE.bazel
@@ -1,4 +1,4 @@
-bazel_dep(name = "protobuf", version = "27.1")
+bazel_dep(name = "protobuf", version = "27.3")
 bazel_dep(name = "rules_proto", version = "6.0.2")
 bazel_dep(name = "rules_proto_grpc_python", version = "0.0.0.rpg.version.placeholder")
 bazel_dep(name = "rules_python", version = "0.34.0")