Stop Wordpress from "guessing" redirects for nonexistent URLs

Question

Wordpress sometimes "guesses" a redirection for a nonexistent page slug if the slug is at the beginning of another URL. After some searching, my hypothesis is that this part of the canonical redirection functionality, which can be disabled using this code:

remove_filter('template_redirect', 'redirect_canonical'); 

However, I like the idea of canonical redirection, and would prefer not to turn it off entirely. Is there a way to only disable the slug "guessing"? I would prefer a 404 over an incorrect 301.

Answer 1

It's a bit hacky, but this should work:

function no_redirect_guess_404_permalink( $header ){
    global $wp_query;

    if( is_404() )
        unset( $wp_query->query_vars['name'] );

    return $header;
}

add_filter( 'status_header', 'no_redirect_guess_404_permalink' );

Answer 2

There is now a filter to control this functionality

add_filter( 'do_redirect_guess_404_permalink', '__return_false');

https://developer.wordpress.org/reference/hooks/do_redirect_guess_404_permalink/