---
title: "CVE-2026-56290: Joomlack Page Builder Improper Access Control Vulnerability"
url: https://erroneo.us/security/cve/CVE-2026-56290/
description: "CVE-2026-56290 (Joomlack Page Builder): Exploited in the wild (CISA KEV). Joomla Extension - joomlack.fr - Unauthenticated file upload in Page Builder CK…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-06-29
date_modified: 2026-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-56290"
kev: true
cvss: 10
epss: 0.30866
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-56290: Joomlack Page Builder Improper Access Control Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Joomlack Page Builder. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-07-07, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-07-10 ; treat that as the outer limit, not the target.
- EPSS 30.9% , percentile 98: FIRST’s model estimates a 30.9% chance of exploitation activity in the next 30 days, higher than 98% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Editorial verdict: Check exposure. Page Builder CK CVE-2026-56290: Exploited Joomla Upload RCE — Only Joomla sites running Page Builder CK are at risk, but for them this is an emergency: an unauthenticated web-shell upload exploited within hours of the patch, with an incomplete first fix, so update to 3.6.5 or later and hunt for shells.

## What it is

Joomla Extension - joomlack.fr - Unauthenticated file upload in Page Builder CK extension

## Affected products (CVE record)

- joomlack.fr JoomlaCK.fr Page Builder CK extension for Joomla: 1.0-3.6.0

## Severity

- Joomla CVSS 4.0: 10 `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`

## Exploitation

- CISA KEV: added 2026-07-07; federal due date 2026-07-10. Known ransomware use: Unknown.
- CISA required action: 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.
- CISA SSVC assessment: exploitation active , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 30.87% probability of exploitation activity in the next 30 days; percentile 98.

## Sources

- [forum.joomlack.fr](https://forum.joomlack.fr/index.php/page-builder-ck/21627-nouvelle-version-de-pbck-et-joomla-3)
- [Listed in CISA KEV notes (joomlack.fr)](https://www.joomlack.fr/en/joomla-extensions/page-builder-ck)
- [CVE.org record CVE-2026-56290](https://www.cve.org/CVERecord?id=CVE-2026-56290)
- [NVD entry CVE-2026-56290](https://nvd.nist.gov/vuln/detail/CVE-2026-56290)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-56290)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk)
- [joomlack.fr](https://www.joomlack.fr/)
- [mysites.guru](https://mysites.guru/blog/pagebuilderck-unauthenticated-file-upload-rce/)

---
Source page: https://erroneo.us/security/cve/CVE-2026-56290/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt