mysql_error() can lead to Cross Site Scripting attacks    
 Affected.scr..: PHP4 <= 4.4.4  PHP5 <= 5.1.6
 Advisory.ID...: 11060920
 Risk.level....: Low
 Vendor.Status.: Unpatched

PHP: Hypertext Preprocessor is an open source server side
programming language extensively used for web scripts and to
process data passed via the Common Gateway Interface from
HTML forms etc. PHP can be written as scripts that reside on
the server and may produce HTML output that downloads to the
web browser. Alternatively, PHP can be embedded within HTML
pages that are then saved with a .php file extension. The PHP
sections of the page are then parsed by the PHP engine on the
server and the PHP code stripped out before the page is
downloaded to the web browser. The name is a bit of a
programming joke (if there is sucha thing) since it's a
recursive acronym i.e. the P in PHP stands for PHP.

The goal of the mysql_error() function is to return the error
text from the last MySQL function. This function can lead to
Cross Site Scripting attacks. To conduct this attack, some
parameters are required. If an mysql function use a bad parameter
provided by the attacker and if the mysql_error() result is
returned to the user, this can be exploited to conduct Cross
Site Scripting attack. This can be useful if the attacker has
a restricted access to an mysql function.

<?php  //?db=<script>alert(666)</script>
$link = mysql_connect("localhost", "root", "");
mysql_select_db($db, $link);
echo mysql_errno($link) . ": " . mysql_error($link). "\n";

Mysql functions list.:
Discussion on

No response from PHP Team.

06. Sept. 2006 - Vendor contacted
20. Sept. 2006 - Public disclosure

Author: DarkFig
E-mail: gmdarkfig[*]gmail[*]com (fr/en)