diff -U0 openssh-6.4p1/ChangeLog.3des-dh-size openssh-6.4p1/ChangeLog
--- openssh-6.4p1/ChangeLog.3des-dh-size	2014-01-28 14:15:25.178358616 +0100
+++ openssh-6.4p1/ChangeLog	2014-01-28 14:18:24.678444650 +0100
@@ -0,0 +1,15 @@
+20140126
+ - OpenBSD CVS Sync
+   - dtucker@cvs.openbsd.org 2014/01/25 10:12:50
+     [cipher.c cipher.h kex.c kex.h kexgexc.c]
+     Add a special case for the DH group size for 3des-cbc, which has an
+     effective strength much lower than the key size.  This causes problems
+     with some cryptlib implementations, which don't support group sizes larger
+     than 4k but also don't use the largest group size it does support as
+     specified in the RFC.  Based on a patch from Petr Lautrbach at Redhat,
+     reduced by me with input from Markus.  ok djm@ markus@
+   - markus@cvs.openbsd.org 2014/01/25 20:35:37
+     [kex.c]
+     dh_need needs to be set to max(seclen, blocksize, ivlen, mac_len)
+     ok dtucker@, noted by mancha
+
diff -up openssh-6.4p1/cipher.c.3des-dh-size openssh-6.4p1/cipher.c
--- openssh-6.4p1/cipher.c.3des-dh-size	2014-01-28 14:15:25.101359008 +0100
+++ openssh-6.4p1/cipher.c	2014-01-28 14:17:48.119630792 +0100
@@ -1,4 +1,4 @@
-/* $OpenBSD: cipher.c,v 1.89 2013/05/17 00:13:13 djm Exp $ */
+/* $OpenBSD: cipher.c,v 1.94 2014/01/25 10:12:50 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -144,6 +144,14 @@ cipher_keylen(const Cipher *c)
 }
 
 u_int
+cipher_seclen(const Cipher *c)
+{
+	if (strcmp("3des-cbc", c->name) == 0)
+		return 14;
+	return cipher_keylen(c);
+}
+
+u_int
 cipher_authlen(const Cipher *c)
 {
 	return (c->auth_len);
diff -up openssh-6.4p1/cipher.h.3des-dh-size openssh-6.4p1/cipher.h
--- openssh-6.4p1/cipher.h.3des-dh-size	2014-01-28 14:15:25.178358616 +0100
+++ openssh-6.4p1/cipher.h	2014-01-28 14:17:17.858784879 +0100
@@ -1,4 +1,4 @@
-/* $OpenBSD: cipher.h,v 1.40 2013/04/19 01:06:50 djm Exp $ */
+/* $OpenBSD: cipher.h,v 1.44 2014/01/25 10:12:50 dtucker Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -95,6 +95,7 @@ void	 cipher_cleanup(CipherContext *);
 int	 cipher_set_key_string(CipherContext *, const Cipher *, const char *, int);
 u_int	 cipher_blocksize(const Cipher *);
 u_int	 cipher_keylen(const Cipher *);
+u_int	 cipher_seclen(const Cipher *);
 u_int	 cipher_authlen(const Cipher *);
 u_int	 cipher_ivlen(const Cipher *);
 u_int	 cipher_is_cbc(const Cipher *);
diff -up openssh-6.4p1/kex.c.3des-dh-size openssh-6.4p1/kex.c
--- openssh-6.4p1/kex.c.3des-dh-size	2014-01-28 14:15:25.165358682 +0100
+++ openssh-6.4p1/kex.c	2014-01-28 14:19:22.038152586 +0100
@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.c,v 1.91 2013/05/17 00:13:13 djm Exp $ */
+/* $OpenBSD: kex.c,v 1.97 2014/01/25 20:35:37 markus Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  *
@@ -494,7 +494,7 @@ kex_choose_conf(Kex *kex)
 	char **my, **peer;
 	char **cprop, **sprop;
 	int nenc, nmac, ncomp;
-	u_int mode, ctos, need, authlen;
+	u_int mode, ctos, need, dh_need, authlen;
 	int first_kex_follows, type;
 
 	my   = kex_buf2prop(&kex->my, NULL);
@@ -545,20 +545,21 @@ kex_choose_conf(Kex *kex)
 	choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
 	choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
 	    sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
-	need = 0;
+	need = dh_need = 0;
 	for (mode = 0; mode < MODE_MAX; mode++) {
 		newkeys = kex->newkeys[mode];
-		if (need < newkeys->enc.key_len)
-			need = newkeys->enc.key_len;
-		if (need < newkeys->enc.block_size)
-			need = newkeys->enc.block_size;
-		if (need < newkeys->enc.iv_len)
-			need = newkeys->enc.iv_len;
-		if (need < newkeys->mac.key_len)
-			need = newkeys->mac.key_len;
+		need = MAX(need, newkeys->enc.key_len);
+		need = MAX(need, newkeys->enc.block_size);
+		need = MAX(need, newkeys->enc.iv_len);
+		need = MAX(need, newkeys->mac.key_len);
+		dh_need = MAX(dh_need, cipher_seclen(newkeys->enc.cipher));
+		dh_need = MAX(dh_need, newkeys->enc.block_size);
+		dh_need = MAX(dh_need, newkeys->enc.iv_len);
+		dh_need = MAX(dh_need, newkeys->mac.key_len);
 	}
 	/* XXX need runden? */
 	kex->we_need = need;
+	kex->dh_need = dh_need;
 
 	/* ignore the next message if the proposals do not match */
 	if (first_kex_follows && !proposals_match(my, peer) &&
diff -up openssh-6.4p1/kexgexc.c.3des-dh-size openssh-6.4p1/kexgexc.c
--- openssh-6.4p1/kexgexc.c.3des-dh-size	2014-01-28 14:15:25.165358682 +0100
+++ openssh-6.4p1/kexgexc.c	2014-01-28 14:19:09.718215323 +0100
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexgexc.c,v 1.13 2013/05/17 00:13:13 djm Exp $ */
+/* $OpenBSD: kexgexc.c,v 1.16 2014/01/25 10:12:50 dtucker Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
@@ -60,7 +60,7 @@ kexgex_client(Kex *kex)
 	int min, max, nbits;
 	DH *dh;
 
-	nbits = dh_estimate(kex->we_need * 8);
+	nbits = dh_estimate(kex->dh_need * 8);
 
 	if (datafellows & SSH_OLD_DHGEX) {
 		/* Old GEX request */
diff -up openssh-6.4p1/kex.h.3des-dh-size openssh-6.4p1/kex.h
--- openssh-6.4p1/kex.h.3des-dh-size	2014-01-28 14:15:25.142358799 +0100
+++ openssh-6.4p1/kex.h	2014-01-28 14:18:49.431318614 +0100
@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.h,v 1.56 2013/07/19 07:37:48 markus Exp $ */
+/* $OpenBSD: kex.h,v 1.61 2014/01/25 10:12:50 dtucker Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -125,6 +125,7 @@ struct Kex {
 	u_int	session_id_len;
 	Newkeys	*newkeys[MODE_MAX];
 	u_int	we_need;
+	u_int	dh_need;
 	int	server;
 	char	*name;
 	int	hostkey_type;