Actively exploited · Published Jun 29, 2026 · Assigned by Joomla

CVE-2026-56290Joomla Extension - joomlack.fr - Unauthenticated file upload in Page Builder CK extension < 3.6.0

Critical 10.0 Exploited

In plain English

A critical-severity unrestricted file upload in JoomlaCK.fr Page Builder CK extension for Joomla from joomlack.fr. Attackers are actively exploiting it in the wild (listed by CISA on July 7, 2026). The chance it is exploited in the next 30 days is estimated at 30.9% (higher than 98% of all known vulnerabilities). Ready-made attack tooling exists: Nuclei, public proof-of-concept code. Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Severity (CVSS 4.0)10.0Critical
Exploit odds (30 days)30.9%top 1.7% of all CVEs
Exploited in the wildYesCISA KEV since Jul 7, 2026
Attack tooling2Nuclei, Public PoC

CISA guidance

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Federal agencies must remediate by Jul 10, 2026.

Official description

Joomla Extension - joomlack.fr - Unauthenticated file upload in Page Builder CK extension < 3.6.0 - The Joomla extension Page Builder CK is vulnerable to an unauthenticated arbitrary file upload that allows uploading executable files and leads to full RCE.

Affected products (as reported)

Weakness: CWE-434 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/AU:Y/U:Red

References