diff -up gnutls-2.12.14/lib/gnutls_cipher.c.packet gnutls-2.12.14/lib/gnutls_cipher.c
--- gnutls-2.12.14/lib/gnutls_cipher.c.packet	2011-09-18 00:16:53.000000000 +0200
+++ gnutls-2.12.14/lib/gnutls_cipher.c	2012-03-23 13:29:24.077877489 +0100
@@ -511,14 +511,13 @@ _gnutls_ciphertext2compressed (gnutls_se
         {
           ciphertext.size -= blocksize;
           ciphertext.data += blocksize;
-
-          if (ciphertext.size == 0)
-            {
-              gnutls_assert ();
-              return GNUTLS_E_DECRYPTION_FAILED;
-            }
         }
 
+      if (ciphertext.size < hash_size)
+        {
+          gnutls_assert ();
+          return GNUTLS_E_DECRYPTION_FAILED;
+        }
       pad = ciphertext.data[ciphertext.size - 1] + 1;   /* pad */
 
       if ((int) pad > (int) ciphertext.size - hash_size)