diff --git a/CHANGES.txt b/CHANGES.txt
index 8d003b4131..5bcf25667c 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -97,6 +97,7 @@
  * Add guardrail for ALTER TABLE ADD / DROP / REMOVE column operations (CASSANDRA-17495)
  * Rename DisableFlag class to EnableFlag on guardrails (CASSANDRA-17544)
 Merged from 4.1:
+ * Fix PAXOS2_COMMIT_AND_PREPARE_RSP serialisation AssertionError (CASSANDRA-18164)
  * Streaming progress virtual table lock contention can trigger TCP_USER_TIMEOUT and fail streaming (CASSANDRA-18110)
  * Fix perpetual load of denylist on read in cases where denylist can never be loaded (CASSANDRA-18116)
 Merged from 4.0:
diff --git a/src/java/org/apache/cassandra/gms/Gossiper.java b/src/java/org/apache/cassandra/gms/Gossiper.java
index d05ef94bea..a19954adec 100644
--- a/src/java/org/apache/cassandra/gms/Gossiper.java
+++ b/src/java/org/apache/cassandra/gms/Gossiper.java
@@ -1143,6 +1143,14 @@ public class Gossiper implements IFailureDetectionEventListener, GossiperMBean
         return endpointStateMap.get(ep);
     }
 
+    public EndpointState copyEndpointStateForEndpoint(InetAddressAndPort ep)
+    {
+        EndpointState epState = endpointStateMap.get(ep);
+        if (epState == null)
+            return null;
+        return new EndpointState(epState);
+    }
+
     public ImmutableSet<InetAddressAndPort> getEndpoints()
     {
         return ImmutableSet.copyOf(endpointStateMap.keySet());
diff --git a/src/java/org/apache/cassandra/service/paxos/Paxos.java b/src/java/org/apache/cassandra/service/paxos/Paxos.java
index ee5b27e407..5bdb75c78f 100644
--- a/src/java/org/apache/cassandra/service/paxos/Paxos.java
+++ b/src/java/org/apache/cassandra/service/paxos/Paxos.java
@@ -1156,8 +1156,8 @@ public class Paxos
             return emptyMap();
 
         Map<InetAddressAndPort, EndpointState> endpoints = Maps.newHashMapWithExpectedSize(remoteElectorate.size() + localElectorate.size());
-        remoteElectorate.forEach(host -> endpoints.put(host, Gossiper.instance.getEndpointStateForEndpoint(host)));
-        localElectorate.forEach(host -> endpoints.putIfAbsent(host, Gossiper.instance.getEndpointStateForEndpoint(host)));
+        remoteElectorate.forEach(host -> endpoints.put(host, Gossiper.instance.copyEndpointStateForEndpoint(host)));
+        localElectorate.forEach(host -> endpoints.putIfAbsent(host, Gossiper.instance.copyEndpointStateForEndpoint(host)));
 
         return endpoints;
     }