diff --git a/tools/kwbimage.c b/tools/kwbimage.c
index 94b7685392..6abb9f2d5c 100644
--- a/tools/kwbimage.c
+++ b/tools/kwbimage.c
@@ -1969,6 +1969,9 @@ static int kwbimage_verify_header(unsigned char *ptr, int image_size,
 	uint32_t size;
 	uint8_t csum;
 
+	if (header_size > 192*1024)
+		return -FDT_ERR_BADSTRUCTURE;
+
 	if (header_size > image_size)
 		return -FDT_ERR_BADSTRUCTURE;