Impact

Authenticated users with lower privileges (like contributors) can inject JavaScript code in the block editor, which is executed within the dashboard. It can lead to an admin opening the affected post in the editor leading to XSS.

Patches

This has been patched in WordPress 5.3.1, along with all the previous affected WordPress versions via a minor release. Automatic updates are enabled by default for minor releases and we strongly recommend that you keep them enabled.

References

• https://wordpress.org/news/2019/12/wordpress-5-3-1-security-and-maintenance-release/
• https://hackerone.com/reports/731301

For more information

If you have any questions or comments about this advisory:

• Open an issue on HackerOne