diff --git a/wp-includes/theme.php b/wp-includes/theme.php
index b52fb3ef7f..ef49f07e14 100644
--- a/wp-includes/theme.php
+++ b/wp-includes/theme.php
@@ -1179,6 +1179,20 @@ function get_header_image() {
 		$url = get_random_header_image();
 	}
 
+	/**
+	 * Filters the header image URL.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string $url Header image URL.
+	 */
+	$url = apply_filters( 'get_header_image', $url );
+
+	if ( ! is_string( $url ) ) {
+		return false;
+	}
+
+	$url = trim( $url );
 	return sanitize_url( set_url_scheme( $url ) );
 }
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index f1b55dd726..75295955c5 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-53740';
+$wp_version = '6.1-alpha-53741';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.