WordPress at a glance
action is not described

auth_cookie_bad_username action-hook . WP 2.7.0

Fires if a bad username is entered in the user authentication process.

Usage

add_action( 'auth_cookie_bad_username', 'action_function_name_3321' );
function action_function_name_3321( $cookie_elements ){
	// action...
}
$cookie_elements(array)
An array of data for the authentication cookie.

Where the hook is called

wp_validate_auth_cookie()
auth_cookie_bad_username
wp-includes/pluggable.php 643
do_action( 'auth_cookie_bad_username', $cookie_elements );

Where the hook is used (in WP core)

wp-includes/default-filters.php 262
add_action( 'auth_cookie_bad_username', 'rest_cookie_collect_status' );