Wednesday, Nov 25th, 2020
Security risk: 
Advisory ID: 
Arbitrary PHP code execution
Versions affected: 
  • Backdrop Core 1.17.x versions prior to 1.17.4
  • Backdrop Core 1.16.x versions prior to 1.16.6

Backdrop versions 1.15 and prior do not receive security coverage.


The Backdrop CMS project uses the PEAR Archive_Tar library. The PEAR Archive_Tar library has released a security update that impacts Backdrop. For more information please see the CVE's linked here.

Multiple vulnerabilities are possible if Backdrop is configured to allow .tar, .tar.gz, .bz2 or .tlz file uploads and processes them.

To mitigate this issue, prevent untrusted users from uploading .tar, .tar.gz, .bz2 or .tlz files.



Upgrade your site to the most recent version of Backdrop core. Download available on the Backdrop CMS 1.17.4 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.

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  • Scroll down to the "Email notifications" section
  • Check the box labeled "Receive security announcements for core and contrib projects"