How might I sanitize an XML file before WP Import? (Does wordpress verify or clean text when importing from an XML document? )

From quick look at the code the post data mostly goes straight into wp_insert_post(), which is a low level function and serves to just store whatever you give it.

If you want to enforce the check you could make use of wp_import_post_data_raw filter and probably wp_kses_post().

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)