Uses
| Uses | Description | 
|---|---|
| wp-admin/includes/misc.php: admin_referrer_policy | Filters the admin referrer policy header value. | 
| wp-includes/plugin.php: apply_filters() | Calls the callback functions that have been added to a filter hook. | 
Send a referrer policy header so referrers are not sent externally from administration screens.
File: wp-admin/includes/misc.php
function wp_admin_headers() {
	$policy = 'strict-origin-when-cross-origin';
	/**
	 * Filters the admin referrer policy header value.
	 *
	 * @since 4.9.0
	 * @since 4.9.5 The default value was changed to 'strict-origin-when-cross-origin'.
	 *
	 * @link https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy
	 *
	 * @param string $policy The admin referrer policy header value. Default 'strict-origin-when-cross-origin'.
	 */
	$policy = apply_filters( 'admin_referrer_policy', $policy );
	header( sprintf( 'Referrer-Policy: %s', $policy ) );
}  | Version | Description | 
|---|---|
| 4.9.0 | Introduced. | 
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Licensed under the GNU GPLv2+ License.
    https://developer.wordpress.org/reference/functions/wp_admin_headers