diff --git a/contribs/hybridsim/pom.xml b/contribs/hybridsim/pom.xml
index f58a572c939..b480aa197dd 100644
--- a/contribs/hybridsim/pom.xml
+++ b/contribs/hybridsim/pom.xml
@@ -10,7 +10,7 @@
   <name>hybridsim</name>
 
   <properties>
-    <protobuf.version>4.27.2</protobuf.version>
+    <protobuf.version>4.28.0</protobuf.version>
     <grpc.version>1.65.1</grpc.version>
   </properties>
 
diff --git a/contribs/protobuf/pom.xml b/contribs/protobuf/pom.xml
index a2c8a4ef62b..a08c2d527c8 100644
--- a/contribs/protobuf/pom.xml
+++ b/contribs/protobuf/pom.xml
@@ -11,7 +11,7 @@
     <name>protobuf</name>
 
     <properties>
-        <protobuf.version>4.27.2</protobuf.version>
+        <protobuf.version>4.28.0</protobuf.version>
     </properties>
 
     <dependencies>