CVE-2013-2174: Heap-based buffer overflow in the curl_easy_unescape function

in lib/escape.c in cURL and libcurl 7.7 through 7.30.0 allows remote

attackers to cause a denial of service (application crash) or possibly

execute arbitrary code via a crafted string ending in a "%" (percent)

character.

CVE webpage for this problem:

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-2174

Relevant upstream patch at:

https://github.com/bagder/curl/commit/192c4f788d48f82c03e9cef40013f34370e90737

--- lib/escape.c.orig	2013-08-20 17:09:51.197431224 -0700

+++ lib/escape.c	2013-08-20 17:10:43.746809478 -0700

@@ -5,7 +5,7 @@

  *                            | (__| |_| |  _ <| |___

  *                             \___|\___/|_| \_\_____|

  *

- * Copyright (C) 1998 - 2011, Daniel Stenberg, <[email protected]>, et al.

+ * Copyright (C) 1998 - 2013, Daniel Stenberg, <[email protected]>, et al.

  *

  * This software is licensed as described in the file COPYING, which

  * you should have received as part of this distribution. The terms

@@ -159,7 +159,8 @@

   while(--alloc > 0) {

     in = *string;

-    if(('%' == in) && ISXDIGIT(string[1]) && ISXDIGIT(string[2])) {

+    if(('%' == in) && (alloc > 2) &&

+       ISXDIGIT(string[1]) && ISXDIGIT(string[2])) {

       /* this is two hexadecimal digits following a '%' */

       char hexstr[3];

       char *ptr;