The actual leaks might be related to php_phongo_bson_to_zval_ex(). This was observed in several BSON binary corpus tests that decode invalid canonical BSON strings (PHPC-2634). Those tests are marked as XFAIL pending this investigation.

Additionally, when var_dump()-ing a Document instance with invalid BSON, an empty object may still be dumped despite an exception also being thrown. For example, some of the corpus tests generate the following output:

object(MongoDB\BSON\Document)#2 (0) {
}
OK: Got MongoDB\Driver\Exception\InvalidArgumentException