diff --git a/g10/parse-packet.c b/g10/parse-packet.c
index e4e524c71..c0b6ad6d8 100644
--- a/g10/parse-packet.c
+++ b/g10/parse-packet.c
@@ -40,6 +40,12 @@
 #define MAX_EXTERN_MPI_BITS 16384
 #endif
 
+/* Maximum length of packets to avoid excessive memory allocation.  */
+#define MAX_KEY_PACKET_LENGTH     (256 * 1024)
+#define MAX_UID_PACKET_LENGTH     (  2 * 1024)
+#define MAX_COMMENT_PACKET_LENGTH ( 64 * 1024)
+#define MAX_ATTR_PACKET_LENGTH    ( 16 * 1024*1024)
+
 
 static int mpi_print_mode;
 static int list_mode;
@@ -1663,6 +1669,13 @@ parse_key( IOBUF inp, int pkttype, unsigned long pktlen,
         rc = G10ERR_INVALID_PACKET;
 	goto leave;
     }
+    else if (pktlen > MAX_KEY_PACKET_LENGTH) {
+        log_error ("packet(%d) too large\n", pkttype);
+        if (list_mode)
+            fputs (":key packet: [too large]\n", listfp);
+        rc = G10ERR_INVALID_PACKET;
+        goto leave;
+    }
 
     timestamp = read_32(inp); pktlen -= 4;
     if( is_v4 ) {
@@ -2083,7 +2096,7 @@ parse_user_id( IOBUF inp, int pkttype, unsigned long pktlen, PACKET *packet )
        allocatable, and a very large pktlen could actually cause our
        allocation to wrap around in xmalloc to a small number. */
 
-    if(pktlen>2048)
+    if (pktlen > MAX_UID_PACKET_LENGTH)
       {
 	log_error("packet(%d) too large\n", pkttype);
 	iobuf_skip_rest(inp, pktlen, 0);
@@ -2152,6 +2165,19 @@ parse_attribute( IOBUF inp, int pkttype, unsigned long pktlen, PACKET *packet )
 {
     byte *p;
 
+    (void)pkttype;
+
+    /* We better cap the size of an attribute packet to make DoS not
+       too easy.  16MB should be more then enough for one attribute
+       packet (ie. a photo).  */
+    if (pktlen > MAX_ATTR_PACKET_LENGTH) {
+        log_error ("packet(%d) too large\n", pkttype);
+        if (list_mode)
+          fprintf (listfp, ":attribute packet: [too large]\n");
+        iobuf_skip_rest (inp, pktlen, 0);
+        return G10ERR_INVALID_PACKET;
+      }
+
 #define EXTRA_UID_NAME_SPACE 71
     packet->pkt.user_id = xmalloc_clear(sizeof *packet->pkt.user_id
 					+ EXTRA_UID_NAME_SPACE);
@@ -2186,7 +2212,7 @@ parse_comment( IOBUF inp, int pkttype, unsigned long pktlen, PACKET *packet )
        overflow in the malloc below.  Comment packets are actually not
        anymore define my OpenPGP and we even stopped to use our
        private comment packet. */
-    if (pktlen>65536)
+    if (pktlen > MAX_COMMENT_PACKET_LENGTH)
       {
 	log_error ("packet(%d) too large\n", pkttype);
 	iobuf_skip_rest (inp, pktlen, 0);