Wednesday, Aug 7th, 2019
Advisory ID: 
Security risk: 
Moderately Critical
Cross Site Scripting
Versions affected: 
  • Backdrop Core 1.13.x versions prior to 1.13.3
  • Backdrop Core 1.12.x versions prior to 1.12.8

Backdrop CMS doesn't sufficiently filter output when displaying certain block labels created by administrators. An attacker could potentially craft a specialized label, then have an administrator execute scripting when administering a layout.

This issue is mitigated by the attacker requiring permission to create custom blocks on the site, which is typically an administrative permission.


Upgrade your site to the most recent version of Backdrop core. Download available on the Backdrop CMS 1.13.3 release page. See the update instructions, if needed.

Fixed By: 
Coordinated By: 

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