Multiples vulnerabilidades estas sacudiendo phpbb en estos ultimos dias, entre ellas, esta que permite realizar injection sqp y ataques XXS:

Exploit

admin_smilies.php?mode=edit&id=[SQL]
admin_smilies.php?mode=delete&id=[SQL]
admin_smilies.php?mode=edit&id=[XSS]
admin_smilies.php?mode=delete&id=[XSS]
admin_styles.php?mode=edit&style_id=[SQL]
admin_styles.php?mode=delete&style_id=[SQL]
admin_styles.php?mode=edit&style_id=[XSS]
admin_styles.php?mode=delete&style_id=[XSS]

Para mas Info: Securityfocus