You will notice in short order if you import products into Cubecart, into categories, you cannot quickly delete that category without first deleting the products. In testing, the filter under View Products in Cubecart 4, 
does not always yield a true listing of products and therefore, cannot be easily deleted en masse. What is one to do?
1. Always backup your database before making any changes.
2. Login to phpmyadmin or your database admin (via Webadmin) if you have access.
Taken courtesy of the cubecart forums to spread the word: 
A minor cross site scripting vulnerability has been reported in all CubeCart v4 releases.
Reports:
http://secunia.com/advisories/29532/
http://www.securityfocus.com/bid/28452
This security hole exists due to a bug in the global variable sanitation function of the ini.inc.php file. Please patch this at the first opportunity either using the manual or auto fix below.
Manual Fix (All 4.x.x Releases)
Open ini.inc.php and find at around line 134:
CODE
$data[$key] = $this->safety($val);
}
return true;
Replace with:
CODE
If you would like to remove products count from category box just remove this:
({DATA.noProducts})
in skins/YOUR-SKIN/styleTemplates/boxes/categories.tpl. Don’t forget to clean cache if you use this feature and would like to see the results immediately. Clear Cache feature you’ll find in the same page as “Rebuilt category product count” button.
I found a slight bug in Cubecart 4. When adding products using the manage categories, or I should say assigning a product to a new category… If I keep the manage categories window open, After finishing selecting multiple categories for that product, I move to another product. Since there are alot of categories, it requires clicking to go to the next page, etc.
I noticed that when adding a product to multiple categories, the item would show up as two items – the category would reflect two widgets in x category when there was only one.
If you are seeing something like this in your Cubecart or server logs:
[Mon Mar 03 20:27:46 2008] [error] [client 69.47.58.156] PHP Warning: parse_url(/index.php?main_page=http://joioiskioeriyyskwkdwjsdfewis.land.ru/.html/body?) [<a href='function.parse-url'>function.parse-url</a>]: Unable to parse url in /var/www/vhosts/YOURSITE.com/httpdocs/includes/sslSwitch.inc.php on line 36
Here is a fix to suppress the error:
edit file includes\sslSwitch.inc.php
FIND: $url_elements = parse_url($_SERVER['REQUEST_URI']);
REPLACE WITH: $url_elements = @parse_url($_SERVER['REQUEST_URI']);
(fixed in MP not in KN)
According to cubecart support staff:
That will indeed suppress the warning, however it is not a bug…at least not in CubeCart. It is a PHP4 bug (we are using php 5.x!), but it doesn’t cause any problems, just the warning. Thanks!
To change the default setting for mail list sign up to checked to (hopefully) get more people on the sign up list:
Open skins\yourskin\styleTemplates\content/reg.tpl
Find:
CODE
<td colspan=”2″>{LANG_RECIEVE_EMAILS}
<input type=”checkbox” name=”optIn1st”
value=”1″ tabindex=”15″ {VAL_OPTIN1ST_CHECKED}/></td>
Change to:
CODE
<td colspan=”2″>{LANG_RECIEVE_EMAILS}
<input type=”checkbox” name=”optIn1st”
value=”1″ tabindex=”15″ {VAL_OPTIN1ST_CHECKED}/
CHECKED></td>
Depending on your country/location, there may be some legalities to “auto-enable” a customers choice to receive newsletter. Some may view it as not actually an “opt-in”….lol.
Anyway, following this will auto-check the box for a customer, its easy for them to uncheck if desired.