CVE-2024-21726Public exploitNetwork attack vector

Administrator code execution via malformed UTF-8 filtering

Published Feb 20, 2024 · Updated Dec 25, 2024

XSS in Joomla! CMS 3.7.0 through 3.10.14, 4.0.0 through 4.4.2, and 5.0.0 through 5.0.2 allows remote attackers to execute scripts. InputFilter::cleanTags combines mb_strpos offsets with mb_substr slicing, whose conflicting handling of invalid UTF-8 retains attacker-supplied tag bytes. An administrator must open a crafted link; the resulting script can alter a template to execute arbitrary PHP code.

CVSS severity6.5
Medium
EPSS probability48.84%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XSS in Joomla! CMS 3.7.0 through 3.10.14, 4.0.0 through 4.4.2, and 5.0.0 through 5.0.2 allows remote attackers to execute scripts. InputFilter::cleanTags combines mb_strpos offsets with mb_substr slicing, whose conflicting handling of invalid UTF-8 retains attacker-supplied tag bytes. An administrator must open a crafted link; the resulting script can alter a template to execute arbitrary PHP code.

The record

CVE
CVE-2024-21726
Published
Feb 20, 2024
Updated
Dec 25, 2024
Vendor
Joomla! Project
Product
Joomla! CMS
Classifications
CWE-79, T1059.007, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 20, 2024CVE publishedPublication date reported by the CVE source.
  2. Dec 25, 2024Record 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=3.7.0-3.10.14
  2. Affected versionversion=4.0.0-4.4.2
  3. Affected versionversion=5.0.0-5.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Joomla! Project · Joomla! CMSversion=3.7.0-3.10.14; version=4.0.0-4.4.2; version=5.0.0-5.0.2

Published CVSS scores

6.5Joomla! ProjectCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript
T1204.001Malicious Link

Public exploit references

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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