diff --git a/src/lib/spinel/spinel.h b/src/lib/spinel/spinel.h
index 1c0970077..c15968d1d 100644
--- a/src/lib/spinel/spinel.h
+++ b/src/lib/spinel/spinel.h
@@ -345,8 +345,30 @@
 #define SPINEL_PROTOCOL_VERSION_THREAD_MAJOR 4
 #define SPINEL_PROTOCOL_VERSION_THREAD_MINOR 3
 
+/**
+ * @def SPINEL_FRAME_MAX_SIZE
+ *
+ *  The maximum size of SPINEL frame.
+ *
+ */
 #define SPINEL_FRAME_MAX_SIZE 1300
 
+/**
+ * @def SPINEL_FRAME_MAX_COMMAND_HEADER_SIZE
+ *
+ *  The maximum size of SPINEL command header.
+ *
+ */
+#define SPINEL_FRAME_MAX_COMMAND_HEADER_SIZE 4
+
+/**
+ * @def SPINEL_FRAME_MAX_PAYLOAD_SIZE
+ *
+ *  The maximum size of SPINEL command payload.
+ *
+ */
+#define SPINEL_FRAME_MAX_COMMAND_PAYLOAD_SIZE (SPINEL_FRAME_MAX_SIZE - SPINEL_FRAME_MAX_COMMAND_HEADER_SIZE)
+
 /**
  * @def SPINEL_ENCRYPTER_EXTRA_DATA_SIZE
  *
diff --git a/src/ncp/ncp_base_mtd.cpp b/src/ncp/ncp_base_mtd.cpp
index f694deb7b..25efa03fa 100644
--- a/src/ncp/ncp_base_mtd.cpp
+++ b/src/ncp/ncp_base_mtd.cpp
@@ -3397,6 +3397,9 @@ void NcpBase::HandleDatagramFromStack(otMessage *aMessage)
 {
     VerifyOrExit(aMessage != NULL, OT_NOOP);
 
+    // Do not forward frames larger than SPINEL payload size.
+    VerifyOrExit(otMessageGetLength(aMessage) <= SPINEL_FRAME_MAX_COMMAND_PAYLOAD_SIZE, otMessageFree(aMessage));
+
     otMessageQueueEnqueue(&mMessageQueue, aMessage);
 
     // If there is no queued spinel command response, try to write/send