CVE-2021-26038Network attack vector

Privilege escalation via missing installer Super User check

Published Jul 7, 2021 · Updated Feb 25, 2026

Incorrect access control in Joomla! CMS 2.5.0 through 3.9.27 allows remote attackers to invoke installer actions reserved for Super Users. The com_installer install action relies on configurable component ACLs and omits a hardcoded Super User authorization check before processing an installation request. Only sites that delegate com_installer permissions below Super User are exposed; default ACLs already restrict the component to Super Users.

CVSS severity7.5
High
EPSS probability1.00%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect access control in Joomla! CMS 2.5.0 through 3.9.27 allows remote attackers to invoke installer actions reserved for Super Users. The com_installer install action relies on configurable component ACLs and omits a hardcoded Super User authorization check before processing an installation request. Only sites that delegate com_installer permissions below Super User are exposed; default ACLs already restrict the component to Super Users.

The record

CVE
CVE-2021-26038
Published
Jul 7, 2021
Updated
Feb 25, 2026
Vendor
Joomla! Project
Product
Joomla! CMS
Classifications
CWE-754, T1068
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Feb 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.5.0-3.9.27

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Joomla! Project · Joomla! CMSversion=2.5.0-3.9.27

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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