diff --git a/wp-includes/capabilities.php b/wp-includes/capabilities.php
index eb6b3bbace..e6d16e927a 100644
--- a/wp-includes/capabilities.php
+++ b/wp-includes/capabilities.php
@@ -72,11 +72,8 @@ function map_meta_cap( $cap, $user_id, ...$args ) {
 			}
 
 			if ( 'revision' == $post->post_type ) {
-				$post = get_post( $post->post_parent );
-				if ( ! $post ) {
-					$caps[] = 'do_not_allow';
-					break;
-				}
+				$caps[] = 'do_not_allow';
+				break;
 			}
 
 			if ( ( get_option( 'page_for_posts' ) == $post->ID ) || ( get_option( 'page_on_front' ) == $post->ID ) ) {
diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php
index 1b34619130..0a0a88106b 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php
@@ -349,6 +349,11 @@ class WP_REST_Revisions_Controller extends WP_REST_Controller {
 			return $parent;
 		}
 
+		$parent_post_type = get_post_type_object( $parent->post_type );
+		if ( ! current_user_can( $parent_post_type->cap->delete_post, $parent->ID ) ) {
+			return new WP_Error( 'rest_cannot_delete', __( 'Sorry, you are not allowed to delete revisions of this post.' ), array( 'status' => rest_authorization_required_code() ) );
+		}
+
 		$revision = $this->get_revision( $request['id'] );
 		if ( is_wp_error( $revision ) ) {
 			return $revision;
@@ -383,7 +388,12 @@ class WP_REST_Revisions_Controller extends WP_REST_Controller {
 		}
 
 		$post_type = get_post_type_object( 'revision' );
-		return current_user_can( $post_type->cap->delete_post, $revision->ID );
+
+		if ( ! current_user_can( $post_type->cap->delete_post, $revision->ID ) ) {
+			return new WP_Error( 'rest_cannot_delete', __( 'Sorry, you are not allowed to delete this revision.' ), array( 'status' => rest_authorization_required_code() ) );
+		}
+
+		return true;
 	}
 
 	/**
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 73e93054b6..64a34623ca 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.3-alpha-45811';
+$wp_version = '5.3-alpha-45812';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.