CVE-2021-26032Network attack vector

Cross-site scripting via permitted HTML uploads

Published May 26, 2021 · Updated Feb 25, 2026

Cross-site scripting in Joomla! CMS 3.0.0 through 3.9.26 allows remote attackers to run script through uploaded HTML content. MediaHelper::canUpload omits HTML from its executable block list, so it accepts active markup that a browser can execute. Exploitation requires a victim to open attacker-controlled content; the script runs in the Joomla origin and can read or alter data accessible to that victim.

CVSS severity6.1
Medium
EPSS probability0.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Joomla! CMS 3.0.0 through 3.9.26 allows remote attackers to run script through uploaded HTML content. MediaHelper::canUpload omits HTML from its executable block list, so it accepts active markup that a browser can execute. Exploitation requires a victim to open attacker-controlled content; the script runs in the Joomla origin and can read or alter data accessible to that victim.

The record

CVE
CVE-2021-26032
Published
May 26, 2021
Updated
Feb 25, 2026
Vendor
Joomla! Project
Product
Joomla! CMS
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 26, 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=3.0.0-3.9.26

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Joomla! Project · Joomla! CMSversion=3.0.0-3.9.26

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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