diff --git a/common/parse.h b/common/parse.h
index 9bd6850c..41cfa698 100644
--- a/common/parse.h
+++ b/common/parse.h
@@ -59,6 +59,9 @@ struct stream
 /******************************************************************************/
 #define s_check_rem(s, n) ((s)->p + (n) <= (s)->end)
 
+/******************************************************************************/
+#define s_check_rem_out(s, n) ((s)->p + (n) <= (s)->data + (s)->size)
+
 /******************************************************************************/
 #define s_check_end(s) ((s)->p == (s)->end)
 
diff --git a/common/trans.c b/common/trans.c
index 6b762d00..38dba51e 100644
--- a/common/trans.c
+++ b/common/trans.c
@@ -202,6 +202,11 @@ trans_force_read_s(struct trans* self, struct stream* in_s, int size)
   }
   while (size > 0)
   {
+    /* make sure stream has room */
+    if ((in_s->end + size) > (in_s->data + in_s->size))
+    {
+      return 1;
+    }
     rcvd = g_tcp_recv(self->sck, in_s->end, size, 0);
     if (rcvd == -1)
     {
diff --git a/libxrdp/xrdp_iso.c b/libxrdp/xrdp_iso.c
index 7fee92e6..983bfb9a 100644
--- a/libxrdp/xrdp_iso.c
+++ b/libxrdp/xrdp_iso.c
@@ -68,18 +68,34 @@ xrdp_iso_recv_msg(struct xrdp_iso* self, struct stream* s, int* code)
   }
   in_uint8s(s, 1);
   in_uint16_be(s, len);
+  if (len < 4)
+  {
+    return 1;
+  }
   if (xrdp_tcp_recv(self->tcp_layer, s, len - 4) != 0)
   {
     return 1;
   }
+  if (!s_check_rem(s, 2))
+  {
+    return 1;
+  }
   in_uint8s(s, 1);
   in_uint8(s, *code);
   if (*code == ISO_PDU_DT)
   {
+    if (!s_check_rem(s, 1))
+    {
+      return 1;
+    }
     in_uint8s(s, 1);
   }
   else
   {
+    if (!s_check_rem(s, 5))
+    {
+      return 1;
+    }
     in_uint8s(s, 5);
   }
   return 0;
diff --git a/libxrdp/xrdp_mcs.c b/libxrdp/xrdp_mcs.c
index 618a3433..304034d1 100644
--- a/libxrdp/xrdp_mcs.c
+++ b/libxrdp/xrdp_mcs.c
@@ -124,6 +124,10 @@ xrdp_mcs_recv(struct xrdp_mcs* self, struct stream* s, int* chan)
       DEBUG(("  out xrdp_mcs_recv xrdp_iso_recv returned non zero"));
       return 1;
     }
+    if (!s_check_rem(s, 1))
+    {
+      return 1;
+    }
     in_uint8(s, opcode);
     appid = opcode >> 2;
     if (appid == MCS_DPUM) /* Disconnect Provider Ultimatum */
@@ -136,6 +140,10 @@ xrdp_mcs_recv(struct xrdp_mcs* self, struct stream* s, int* chan)
     if (appid == MCS_CJRQ)
     {
       g_writeln("channel join request received");
+      if (!s_check_rem(s, 4))
+      {
+        return 1;
+      }
       in_uint16_be(s, userid);
       in_uint16_be(s, chanid);
       DEBUG(("xrdp_mcs_recv  adding channel %4.4x", chanid));
@@ -160,12 +168,20 @@ xrdp_mcs_recv(struct xrdp_mcs* self, struct stream* s, int* chan)
     DEBUG(("  out xrdp_mcs_recv err got 0x%x need MCS_SDRQ", appid));
     return 1;
   }
+  if (!s_check_rem(s, 6))
+  {
+    return 1;
+  }
   in_uint8s(s, 2);
   in_uint16_be(s, *chan);
   in_uint8s(s, 1);
   in_uint8(s, len);
   if (len & 0x80)
   {
+    if (!s_check_rem(s, 1))
+    {
+      return 1;
+    }
     in_uint8s(s, 1);
   }
   DEBUG(("  out xrdp_mcs_recv"));
@@ -184,16 +200,28 @@ xrdp_mcs_ber_parse_header(struct xrdp_mcs* self, struct stream* s,
 
   if (tag_val > 0xff)
   {
+    if (!s_check_rem(s, 2))
+    {
+      return 1;
+    }
     in_uint16_be(s, tag);
   }
   else
   {
+    if (!s_check_rem(s, 1))
+    {
+      return 1;
+    }
     in_uint8(s, tag);
   }
   if (tag != tag_val)
   {
     return 1;
   }
+  if (!s_check_rem(s, 1))
+  {
+    return 1;
+  }
   in_uint8(s, l);
   if (l & 0x80)
   {
@@ -201,6 +229,10 @@ xrdp_mcs_ber_parse_header(struct xrdp_mcs* self, struct stream* s,
     *len = 0;
     while (l > 0)
     {
+      if (!s_check_rem(s, 1))
+      {
+        return 1;
+      }
       in_uint8(s, i);
       *len = (*len << 8) | i;
       l--;
@@ -231,6 +263,10 @@ xrdp_mcs_parse_domain_params(struct xrdp_mcs* self, struct stream* s)
   {
     return 1;
   }
+  if (!s_check_rem(s, len))
+  {
+    return 1;
+  }
   in_uint8s(s, len);
   if (s_check(s))
   {
@@ -251,7 +287,7 @@ xrdp_mcs_recv_connect_initial(struct xrdp_mcs* self)
   struct stream* s;
 
   make_stream(s);
-  init_stream(s, 8192);
+  init_stream(s, 16 * 1024);
   if (xrdp_iso_recv(self->iso_layer, s) != 0)
   {
     free_stream(s);
@@ -300,6 +336,11 @@ xrdp_mcs_recv_connect_initial(struct xrdp_mcs* self)
     free_stream(s);
     return 1;
   }
+  if ((len <= 0) || (len > 16 * 1024))
+  {
+    free_stream(s);
+    return 1;
+  }
   /* make a copy of client mcs data */
   init_stream(self->client_mcs_data, len);
   out_uint8a(self->client_mcs_data, s->p, len);
@@ -332,16 +373,31 @@ xrdp_mcs_recv_edrq(struct xrdp_mcs* self)
     free_stream(s);
     return 1;
   }
+  if (!s_check_rem(s, 1))
+  {
+    free_stream(s);
+    return 1;
+  }
   in_uint8(s, opcode);
   if ((opcode >> 2) != MCS_EDRQ)
   {
     free_stream(s);
     return 1;
   }
+  if (!s_check_rem(s, 4))
+  {
+    free_stream(s);
+    return 1;
+  }
   in_uint8s(s, 2);
   in_uint8s(s, 2);
   if (opcode & 2)
   {
+    if (!s_check_rem(s, 2))
+    {
+      free_stream(s);
+      return 1;
+    }
     in_uint16_be(s, self->userid);
   }
   if (!(s_check_end(s)))
@@ -368,6 +424,11 @@ xrdp_mcs_recv_aurq(struct xrdp_mcs* self)
     free_stream(s);
     return 1;
   }
+  if (!s_check_rem(s, 1))
+  {
+    free_stream(s);
+    return 1;
+  }
   in_uint8(s, opcode);
   if ((opcode >> 2) != MCS_AURQ)
   {
@@ -376,6 +437,11 @@ xrdp_mcs_recv_aurq(struct xrdp_mcs* self)
   }
   if (opcode & 2)
   {
+    if (!s_check_rem(s, 2))
+    {
+      free_stream(s);
+      return 1;
+    }
     in_uint16_be(s, self->userid);
   }
   if (!(s_check_end(s)))
@@ -433,15 +499,30 @@ xrdp_mcs_recv_cjrq(struct xrdp_mcs* self)
     free_stream(s);
     return 1;
   }
+  if (!s_check_rem(s, 1))
+  {
+    free_stream(s);
+    return 1;
+  }
   in_uint8(s, opcode);
   if ((opcode >> 2) != MCS_CJRQ)
   {
     free_stream(s);
     return 1;
   }
+  if (!s_check_rem(s, 4))
+  {
+    free_stream(s);
+    return 1;
+  }
   in_uint8s(s, 4);
   if (opcode & 2)
   {
+    if (!s_check_rem(s, 2))
+    {
+      free_stream(s);
+      return 1;
+    }
     in_uint8s(s, 2);
   }
   if (!(s_check_end(s)))
diff --git a/libxrdp/xrdp_sec.c b/libxrdp/xrdp_sec.c
index 381e8435..426816cb 100644
--- a/libxrdp/xrdp_sec.c
+++ b/libxrdp/xrdp_sec.c
@@ -739,15 +739,27 @@ xrdp_sec_process_mcs_data_channels(struct xrdp_sec* self, struct stream* s)
     g_writeln("Processing channel data from client - The channel is off");  
     return 0;
   }
+  if (!s_check_rem(s, 4))
+  {
+    return 1;
+  }
   in_uint32_le(s, num_channels);
+  if (num_channels > 256)
+  {
+    return 1;
+  }
   for (index = 0; index < num_channels; index++)
   {
     channel_item = (struct mcs_channel_item*)
              g_malloc(sizeof(struct mcs_channel_item), 1);
+    if (!s_check_rem(s, 12))
+    {
+      return 1;
+    }
     in_uint8a(s, channel_item->name, 8);
     in_uint32_le(s, channel_item->flags);
     channel_item->chanid = MCS_GLOBAL_CHANNEL + (index + 1);
-    list_add_item(self->mcs_layer->channel_list, (long)channel_item);
+    list_add_item(self->mcs_layer->channel_list, (tintptr)channel_item);
     DEBUG(("got channel flags %8.8x name %s", channel_item->flags,
            channel_item->name));
   }
@@ -765,10 +777,14 @@ xrdp_sec_process_mcs_data(struct xrdp_sec* self)
   int tag = 0;
   int size = 0;
 
-  s = &self->client_mcs_data;
+  s = &(self->client_mcs_data);
   /* set p to beginning */
   s->p = s->data;
   /* skip header */
+  if (!s_check_rem(s, 23))
+  {
+    return 1;
+  }
   in_uint8s(s, 23);
   while (s_check_rem(s, 4))
   {
@@ -893,7 +909,7 @@ xrdp_sec_out_mcs_data(struct xrdp_sec* self)
 
 /*****************************************************************************/
 /* process the mcs client data we received from the mcs layer */
-static void APP_CC
+static int APP_CC
 xrdp_sec_in_mcs_data(struct xrdp_sec* self)
 {
   struct stream* s = (struct stream *)NULL;
@@ -905,12 +921,20 @@ xrdp_sec_in_mcs_data(struct xrdp_sec* self)
   s = &(self->client_mcs_data);
   /* get hostname, its unicode */
   s->p = s->data;
+  if (!s_check_rem(s, 47))
+  {
+    return 1;
+  }
   in_uint8s(s, 47);
   g_memset(client_info->hostname, 0, 32);
   c = 1;
   index = 0;
   while (index < 16 && c != 0)
   {
+    if (!s_check_rem(s, 2))
+    {
+      return 1;
+    }
     in_uint8(s, c);
     in_uint8s(s, 1);
     client_info->hostname[index] = c;
@@ -918,13 +942,22 @@ xrdp_sec_in_mcs_data(struct xrdp_sec* self)
   }
   /* get build */
   s->p = s->data;
+  if (!s_check_rem(s, 43 + 4))
+  {
+    return 1;
+  }
   in_uint8s(s, 43);
   in_uint32_le(s, client_info->build);
   /* get keylayout */
   s->p = s->data;
+  if (!s_check_rem(s, 39 + 4))
+  {
+    return 1;
+  }
   in_uint8s(s, 39);
   in_uint32_le(s, client_info->keylayout);
   s->p = s->data;
+  return 0;
 }
 
 /*****************************************************************************/
@@ -991,7 +1024,10 @@ xrdp_sec_incoming(struct xrdp_sec* self)
             (int)(self->server_mcs_data.end - self->server_mcs_data.data));
 #endif
   DEBUG((" out xrdp_sec_incoming"));
-  xrdp_sec_in_mcs_data(self);
+  if (xrdp_sec_in_mcs_data(self) != 0)
+  {
+    return 1;
+  }
   return 0;
 }