diff --git a/src/channels.c b/src/channels.c
index 0d19b046..8a2702f2 100644
--- a/src/channels.c
+++ b/src/channels.c
@@ -198,6 +198,13 @@ SSH_PACKET_CALLBACK(ssh_packet_channel_open_conf)
     if (rc != SSH_OK)
         goto error;
 
+    if (channel->remote_maxpacket == 0) {
+        SSH_LOG(SSH_LOG_RARE,
+                "Invalid maximum packet size 0 in "
+                "SSH2_MSG_CHANNEL_OPEN_CONFIRMATION");
+        goto error;
+    }
+
     SSH_LOG(SSH_LOG_DEBUG,
             "Received a CHANNEL_OPEN_CONFIRMATION for channel %" PRIu32
             ":%" PRIu32,
diff --git a/src/messages.c b/src/messages.c
index 824b2772..6740d103 100644
--- a/src/messages.c
+++ b/src/messages.c
@@ -1410,10 +1410,21 @@ SSH_PACKET_CALLBACK(ssh_packet_channel_open){
   SSH_LOG(SSH_LOG_PACKET,
       "Clients wants to open a %s channel", type_c);
 
-  ssh_buffer_unpack(packet,"ddd",
-          &msg->channel_request_open.sender,
-          &msg->channel_request_open.window,
-          &msg->channel_request_open.packet_size);
+  rc = ssh_buffer_unpack(packet,
+                         "ddd",
+                         &msg->channel_request_open.sender,
+                         &msg->channel_request_open.window,
+                         &msg->channel_request_open.packet_size);
+  if (rc != SSH_OK){
+      goto error;
+  }
+
+  if (msg->channel_request_open.packet_size == 0) {
+      ssh_set_error(session,
+                    SSH_FATAL,
+                    "Invalid maximum packet size 0 in SSH2_MSG_CHANNEL_OPEN");
+      goto error;
+  }
 
   if (session->session_state != SSH_SESSION_STATE_AUTHENTICATED){
     ssh_set_error(session,SSH_FATAL, "Invalid state when receiving channel open request (must be authenticated)");