WordPress at a glance
filter is not described

wp_authenticate_user filter-hook . WP 2.5.0

Filters whether the given user can be authenticated with the provided $password.

Usage

add_filter( 'wp_authenticate_user', 'filter_function_name_6580', 10, 2 );
function filter_function_name_6580( $user, $password ){
	// filter...

	return $user;
}
$user(WP_User/WP_Error)
WP_User or WP_Error object if a previous callback failed authentication.
$password(string)
Password to check against the user.

Where the hook is called

wp_authenticate_username_password()
wp_authenticate_email_password()
wp-includes/user.php 163
$user = apply_filters( 'wp_authenticate_user', $user, $password );
wp-includes/user.php 233
$user = apply_filters( 'wp_authenticate_user', $user, $password );

Where the hook is used (in WP core)

Does not used.