[calorie]

In local_links.php find:

if ($_REQUEST['action'] == "doeditlink") {

And afterwards find:

		foreach ($pcatid as $p) {
			$DB_site->query("
			INSERT INTO ".THIS_TABLE."linksltoc (linkid, catid)
			VALUES ('$viewlinkid', '$p')
			");
		}

And replace with:

		foreach ($pcatid as $p) {
			$DB_site->query("
			INSERT INTO ".THIS_TABLE."linksltoc (linkid, catid)
			VALUES ($viewlinkid, ".intval($p).")
			");
		}

Maybe it'd be better to check that $pcatid (and other variables) contain valid value(s) before getting to a query. FWIW.