Title: Version 4.0.9
Author: Subrata Sarkar
Published: January 14, 2019

---

# Version 4.0.9

## In this article

 * [Installation/Update Information](https://wordpress.org/documentation/wordpress-version/version-4-0-9/?output_format=md#installation-update-information)
 * [Summary](https://wordpress.org/documentation/wordpress-version/version-4-0-9/?output_format=md#summary)
 * [List of Files Revised](https://wordpress.org/documentation/wordpress-version/version-4-0-9/?output_format=md#list-of-files-revised)

[ Back to top](https://wordpress.org/documentation/wordpress-version/version-4-0-9/?output_format=md#wp--skip-link--target)

On 6 January, 2016, WordPress 4.0.9 was released to the public.See also: other [WordPress Versions](https://codex.wordpress.org/WordPress_Versions).

## 󠀁[Installation/Update Information](https://wordpress.org/documentation/wordpress-version/version-4-0-9/?output_format=md#installation-update-information)󠁿

To download WordPress 4.0.9, update automatically from the Dashboard > Updates menu
in your site’s admin area or visit [https://wordpress.org/download/release-archive/](https://wordpress.org/download/release-archive/).

For step-by-step instructions on installing and updating WordPress:

 * [Updating WordPress](https://codex.wordpress.org/Updating_WordPress)

If you are new to WordPress, we recommend that you begin with the following:

 * [New To WordPress – Where to Start](https://codex.wordpress.org/New_To_WordPress_-_Where_to_Start)
 * [First Steps With WordPress](https://codex.wordpress.org/First_Steps_With_WordPress)
   or [Upgrading WordPress Extended](https://codex.wordpress.org/Upgrading_WordPress_Extended)
 * [WordPress Lessons](https://codex.wordpress.org/WordPress_Lessons)

## 󠀁[Summary](https://wordpress.org/documentation/wordpress-version/version-4-0-9/?output_format=md#summary)󠁿

WordPress versions 4.4 and earlier are affected by a cross-site scripting vulnerability
that could allow a site to be compromised. This was reported by Crtc4L.

## 󠀁[List of Files Revised](https://wordpress.org/documentation/wordpress-version/version-4-0-9/?output_format=md#list-of-files-revised)󠁿

    ```wp-block-preformatted
    /wp-content/plugins
    /readme.html
    /wp-admin/about.php
    /wp-includes/version.php
    /wp-includes/update.php
    /wp-includes/class-wp-theme.php
    ```

First published

January 14, 2019

Last updated