Looks like similar coverage is available at https://www.ancientcontent.com/p/the-wardrobe-in-house-ix-11, which also has links to some primary sources (in Italian) at the bottom of the page.

Not a PHP dev, but it seems calling `extract` is itself potentially insecure. The php docs warn against it (https://www.php.net/manual/en/function.extract.php):

> Do not use extract() on untrusted data, like user input (e.g. $_GET, $_FILES). If you do, make sure you use one of the non-overwriting flags values such as EXTR_SKIP and be aware that you should extract in the same order that's defined in variables_order within the php.ini.

Looks like calling it can shadow previously defined, unrelated variables?

Edit: On re-reading your comment, yes, if $requiredHeaders is previously sanitized then the code is technically safe. But it still presents as an insecure coding practice.

Check the "Freedom of Panorama" article on Wikipedia: https://en.wikipedia.org/wiki/Freedom_of_panorama - lots of restrictions around the world.