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CVE-2026-56290

From Exploited flaws, HARD’s guide to the flaws being used in attacks · Checked
This article is about a flaw in Joomlack Page Builder. For every flaw being used in attacks, see Exploited flaws.

CVE-2026-56290 is a security flaw in Joomlack Page Builder. Attackers can run their own code on Joomlack Page Builder from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 7 Jul 2026.[1]

Joomlack Page Builder is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Joomlack has published a fix or advice.

Description

CISA calls it an improper access control in Joomlack Page Builder. In its words: “Joomlack Page Builder contains an improper access control vulnerability that could allow for remote code execution via unauthenticated arbitrary file upload.”[1]

The CVE record adds: “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.”[2]

The underlying weakness is improper access control (CWE-284), in MITRE’s list of common software weaknesses.

It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]

Affected versions

NVD’s record doesn’t list version ranges for it; Joomlack’s advisory has them[3]. CISA names the product as Joomlack Page Builder.

Most families won’t have Joomlack Page Builder; it’s for whoever looks after IT at work.

Exploitation

CISA added it to its catalog of known exploited vulnerabilities on 7 Jul 2026, 8 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 10 Jul 2026 to fix it.[1]

FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 31%. That’s in the top 2% of the flaws it scores.[4]

CISA assesses it as automatable: attackers can run it against many targets at once.

CISA doesn’t say who was attacked, or how.

Fix

Joomlack has published a fix or advice.[3] CISA’s 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).”[1]

  1. Check whether you use it.Joomlack Page Builder is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
  2. Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 10 Jul 2026 to fix it.
  3. If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.

You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.

Timeline

DateEvent
The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2]
CISA adds it to its catalog of flaws known to be used in attacks.[1]
CISA’s deadline for US government agencies to fix it.[1]
FIRST puts the odds of it being used in attacks in the next 30 days at 31%.[4]

See also

Other improper access control flaws

  • CVE-2015-3306, ProFTPD: improper access control ·
  • CVE-2026-21962, Oracle HTTP Server and Oracle Weblogic Server Proxy Plug-in: improper access control ·
  • CVE-2026-34908, Ubiquiti UniFi OS: improper access control ·
  • CVE-2026-48907, Widget Factory Joomla Content Editor: improper access control ·
  • CVE-2026-35616, Fortinet FortiClient EMS: improper access control ·

Added the same day

  • CVE-2026-55255, Langflow: authorization bypass through user-controlled key ·
  • CVE-2026-48908, JoomShaper SP Page Builder: unrestricted upload of file with dangerous type ·
  • CVE-2026-48282, Adobe ColdFusion: path traversal ·

References

  1. ^ Cybersecurity and Infrastructure Security Agency. “Joomlack Page Builder Improper Access Control Vulnerability”. Known Exploited Vulnerabilities Catalog, added 7 Jul 2026.
  2. ^ National Institute of Standards and Technology. “CVE-2026-56290 Detail”. National Vulnerability Database, published 29 Jun 2026.
  3. ^ Joomlack. Advisories and fixes: joomlack.fr, forum.joomlack.fr.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.309, percentile 98.3, 31 Oct 2026.
  5. CVE Program. “CVE-2026-56290”. The official CVE record.

This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.