Date: 
Wednesday, May 26th, 2021
Advisory ID: 
BACKDROP-SA-CORE-2021-003
Security risk: 
Moderately Critical
Vulnerability: 
Cross Site Scripting
CVE ID: 
CVE-2021-33829
Versions affected: 
  • Backdrop Core 1.19.x versions prior to 1.19.1
  • Backdrop Core 1.18.x versions prior to 1.18.5

Backdrop versions 1.17 and prior do not receive security coverage.

Description: 

Backdrop core uses the third-party CKEditor library. This library has an error in parsing HTML that could lead to an XSS attack.

Update: 2021-06-11: More details are available on CKEditor's blog.

Solution: 

Upgrade your site to the most recent version of Backdrop core. Download available on the Backdrop CMS 1.19.1 release page. See the update instructions, if needed.

Reported By: 
Fixed By: 

Security email list

Backdrop maintains a security mailing list. Whenever a security release comes out, an email will be sent to everyone subscribed to that list, announcing the new release. Please follow the steps below to join the Security email list.

  1. Log in to backdropcms.org
  2. Edit your profile
  3. Switch to the "Subscriptions" tab
  4. Check the box labeled "Security updates"
  5. Save the form