Date: 
Wednesday, Oct 14th, 2026
Advisory ID: 
BACKDROP-SA-CORE-2026-007
Security risk: 
Critical
Vulnerability: 
Cross Site Scripting
Versions affected: 
  • Backdrop Core 1.35.x versions prior to 1.35.2
  • Backdrop Core 1.34.x versions prior to 1.34.6

Backdrop versions 1.33 and prior do not receive security coverage.

Description: 

Backdrop CMS does not sufficiently validate uploaded SVG images to ensure they do not contain potentially dangerous SVG tags. SVG images can contain clickable links or executable scripting. By uploading a crafted SVG, it is possible to execute scripting in the browser when an SVG image is viewed.

This issue is mitigated by the attacker needing to be able to upload SVG images, and that Backdrop embeds all uploaded SVG images within img tags, which prevents script from executing. The SVG must be viewed directly by its URL in order to run any embedded scripting.

A CVE has been requested, and this page will be updated as soon as an official number has been issued.

Solution: 

Update your site to the most recent version of Backdrop core. Download available on the Backdrop CMS 1.35.2 release page. See the update instructions.

Reported By: 
Fixed By: 
Coordinated 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