diff --git a/lib/class-wp-rest-url-details-controller.php b/lib/class-wp-rest-url-details-controller.php
index ee7c1b23a05c71..f0fbae54f54810 100644
--- a/lib/class-wp-rest-url-details-controller.php
+++ b/lib/class-wp-rest-url-details-controller.php
@@ -191,8 +191,19 @@ public function permissions_check() {
 	 * @return string|WP_Error The HTTP response from the remote URL, or an error.
 	 */
 	private function get_remote_url( $url ) {
+
+		// Provide a modified UA string to workaround web properties which block WordPress "Pingbacks".
+		// Why? The UA string used for pingback requests contains `WordPress/` which is very similar
+		// to that used as the default UA string by the WP HTTP API. Therefore requests from this
+		// REST endpoint are being unintentionally blocked as they are misidentified as pingback requests.
+		// By slightly modifying the UA string, but still retaining the "WordPress" identification (via "WP")
+		// we are able to work around this issue.
+		// Example UA string: `WP-URLDetails/5.9-alpha-51389 (+http://localhost:8888)`.
+		$modified_user_agent = 'WP-URLDetails/' . get_bloginfo( 'version' ) . ' (+' . get_bloginfo( 'url' ) . ')';
+
 		$args = array(
 			'limit_response_size' => 150 * KB_IN_BYTES,
+			'user-agent'          => $modified_user_agent,
 		);
 
 		/**