diff --git a/libavformat/imx.c b/libavformat/imx.c
index d203ed7a28..22fca0bdc0 100644
--- a/libavformat/imx.c
+++ b/libavformat/imx.c
@@ -113,6 +113,8 @@ retry:
             imx->first_video_packet_pos = pos;
         break;
     case 0xAA98:
+        if (chunk_size > 256 * 3)
+            return AVERROR_INVALIDDATA;
         for (int i = 0; i < chunk_size / 3; i++) {
             unsigned r = avio_r8(pb) << 18;
             unsigned g = avio_r8(pb) << 10;