From 3be7f3ea3a56d178acf0f7f84ee4ae8cbfee8915 Mon Sep 17 00:00:00 2001
From: John Safranek <john@wolfssl.com>
Date: Fri, 14 Aug 2020 16:27:39 -0700
Subject: [PATCH] Reject DTLS application data messages in epoch 0 as out of
 order.

---
 src/internal.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/internal.c b/src/internal.c
index 3572835ae..0e3d12aaf 100644
--- a/src/internal.c
+++ b/src/internal.c
@@ -8337,9 +8337,12 @@ static int GetRecordHeader(WOLFSSL* ssl, const byte* input, word32* inOutIdx,
     }
 
 #ifdef WOLFSSL_DTLS
-    if (IsDtlsNotSctpMode(ssl) && !DtlsCheckWindow(ssl)) {
+    if (IsDtlsNotSctpMode(ssl)) {
+        if (!DtlsCheckWindow(ssl) ||
+                (ssl->keys.curEpoch == 0 && rh->type == application_data)) {
             WOLFSSL_LEAVE("GetRecordHeader()", SEQUENCE_ERROR);
             return SEQUENCE_ERROR;
+        }
     }
 #endif