CVE-2026-56290

Joomlack Page Builder, a page-builder extension for the Joomla CMS from the Joomlack vendor, contains an improper access control flaw (CWE-284) that permits unauthenticated arbitrary file upload to affected sites. An unauthenticated remote attacker can abuse the upload functionality to place attacker-controlled files, typically executable script files, on the web server and then request them to achieve remote code execution. Successful exploitation yields code execution under the web server's privileges, enabling full compromise of the website and potentially the underlying hosting account or server; ransomware use has not been confirmed. Any Joomla deployment with the affected extension installed is potentially exposed, with internet-facing sites at greatest risk, and CISA has not published specific affected version ranges. The flaw was added to the CISA KEV catalog on 2026-07-07, indicating confirmed in-the-wild exploitation, and it carries a high exploitation likelihood (EPSS 30.4%, 98th percentile), although no public proof-of-concept or detailed technical write-up is known.

What to do: Inventory Joomla sites for the Joomlack Page Builder extension and apply the vendor's fix as soon as it is released, following the CISA required action and BOD 26-04 guidance; if mitigations are unavailable, remove, disable, or restrict the extension - particularly on internet-exposed or cloud-hosted instances - or discontinue use per BOD 26-04. Until patched, review upload directories for unexpected executable files (e.g., potential webshells) and check access logs for unauthenticated upload requests, and limit direct web access to upload paths where feasible.