--- curl-7.11.2/lib/http_ntlm.c	2005-10-14 11:04:25.017979923 +0100
+++ curl-7.11.2/lib/http_ntlm.c	2005-10-14 11:07:29.271188618 +0100
@@ -531,6 +531,13 @@
     size=64;
     ntlmbuf[62]=ntlmbuf[63]=0;
 
+    /* Make sure that the user and domain strings fit in the target buffer
+       before we copy them there. */
+    if(size + userlen + domlen >= sizeof(ntlmbuf)) {
+      failf(conn->data, "user + domain name too big");
+      return CURLE_OUT_OF_MEMORY;
+    }
+
     memcpy(&ntlmbuf[size], domain, domlen);
     size += domlen;