wget http://joomlacode.org/gf/download/frsrelease/16512/72866/Joomla_2.5.1-Stable-Full_Package.tar.gz
mkdir j-2.5.1; cd j-2.5.1
tar -zxvf ../Joomla_2.5.1-Stable-Full_Package.tar.gz
wget http://joomlacode.org/gf/download/frsrelease/16760/72876/Joomla_2.5.2-Stable-Full_Package.tar.gz
mkdir j-2.5.2; cd j-2.5.2 
tar -zxvf ../Joomla_2.5.2-Stable-Full_Package.tar.gz

diff -rN j-2.5.1 j-2.5.2
[...]
71,72c70
diff -r j-2.5.1/plugins/system/redirect/redirect.php j-2.5.2/plugins/system/redirect/redirect.php
<   $db->setQuery('select id from '.$db->quoteName('#__redirect_links')."  where old_url='".$current."'");
>   $db->setQuery('select id from '.$db->quoteName('#__redirect_links')."  where old_url='" . $db->quote($current) . "'");
[...]