diff --git src/wp-includes/class-wp-customize-manager.php src/wp-includes/class-wp-customize-manager.php
index 09e48b2..29d2567 100644
--- src/wp-includes/class-wp-customize-manager.php
+++ src/wp-includes/class-wp-customize-manager.php
@@ -1025,6 +1025,18 @@ final class WP_Customize_Manager {
 			}
 			$validities[ $setting_id ] = $validity;
 		}
+
+		/**
+		 * Filters the result of validating the setting values after each setting's validate method is called.
+		 *
+		 * @see WP_Customize_Setting::validate()
+		 *
+		 * @param array                $validities     Validities for settings, mapping setting ID to validity.
+		 * @param array                $setting_values Unsanitized setting values.
+		 * @param WP_Customize_Manager $wp_customize   Manager.
+		 */
+		$validities = apply_filters( 'customize_setting_validities', $validities, $setting_values, $this );
+
 		return $validities;
 	}