diff --git a/libavcodec/cdgraphics.c b/libavcodec/cdgraphics.c
index d0cc2126ef..d7b85100ae 100644
--- a/libavcodec/cdgraphics.c
+++ b/libavcodec/cdgraphics.c
@@ -280,6 +280,10 @@ static int cdg_decode_frame(AVCodecContext *avctx,
         av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
         return AVERROR(EINVAL);
     }
+    if (buf_size > CDG_HEADER_SIZE + CDG_DATA_SIZE) {
+        av_log(avctx, AV_LOG_ERROR, "buffer too big for decoder\n");
+        return AVERROR(EINVAL);
+    }
 
     ret = avctx->reget_buffer(avctx, &cc->frame);
     if (ret) {