http://rt.openssl.org/Ticket/Display.html?id=1931&user=guest&pass=guest

Index: openssl/ssl/d1_both.c
===================================================================
--- d1_both.c.orig
+++ d1_both.c
@@ -561,7 +561,16 @@ dtls1_process_out_of_seq_message(SSL *s,
 	if ((msg_hdr->frag_off+frag_len) > msg_hdr->msg_len)
 		goto err;
 
-	if (msg_hdr->seq <= s->d1->handshake_read_seq)
+	/* Try to find item in queue, to prevent duplicate entries */
+	pq_64bit_init(&seq64);
+	pq_64bit_assign_word(&seq64, msg_hdr->seq);
+	item = pqueue_find(s->d1->buffered_messages, seq64);
+	pq_64bit_free(&seq64);
+	
+	/* Discard the message if sequence number was already there, is
+	 * too far in the future or the fragment is already in the queue */
+	if (msg_hdr->seq <= s->d1->handshake_read_seq ||
+		msg_hdr->seq > s->d1->handshake_read_seq + 10 || item != NULL)
 		{
 		unsigned char devnull [256];