Firefox logout problem

[anastis]

There is a case where you get logged out/session cleared/cart emptied, due to a combination of WooCommerce + WordPress + Firefox.

Firefox uses prefetching.
https://developer.mozilla.org/en-US/docs/Link_prefetching_FAQ

WordPress adds <link> elements pointing to previous and next pages, in wp_head().
Rel: wp-includes/default-filters.php:204 add_action( 'wp_head', 'adjacent_posts_rel_link_wp_head', 10, 0 );

WooCommerce's logout URL is handled through a page.

Therefore, when viewing a page adjacent to the logout page, WordPress adds the logout url in the header, like <link rel='prev' title='Logout' href='http://www.example.com/logout/' />
Firefox tries to prefetch that page, and since the page is essentially visited, you get logged out.

Possible solutions

1. Hook on _{$adjacent}post_rel_link filter, check if it's the logout url, and return nothing (or something else) if it is.
2. Change the way WooCommerce handles logouts.
3. Add option to unhook adjacent_posts_rel_link_wp_head
4. Convince WordPress to drop adjacent_posts_rel_link_wp_head completely.
5. Convince Firefox to drop prefetching completely.

Hope this helps :)

[maxrice]

What an amusing bug, excellent write up! 👍

[anastis]

Cheers!
Took me a while to find the root causes.