CVE-2026-90918
Received Received - Intake

Cross-Site Scripting in Joomla Core Mail Templates

Publication date: 2026-09-29

Last updated on: 2026-09-29

Assigner: Joomla! Project

Description
Joomla! Core - [20260908] - Core - XSS in HTML Mail Templates in Joomla 4.0.0-5.4.8, 6.0.0-6.1.3 - The mail template feature lacks an escaping mechanism, causing XSS vectors in multiple extensions.

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Meta Information

Published
2026-09-29
Last Modified
2026-09-29
Generated
2026-09-29
AI Q&A
2026-09-29
EPSS Evaluated
N/A
NVD
CVE-2026-90918
EUVD
EUVD-2026-89080

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
joomla core From 4.0.0 (inc) to 6.1.4 (exc)
joomla core From 6.0.0 (inc) to 6.1.4 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Attack-Flow Graph

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Executive Summary

CVE-2026-90918 is a Cross-Site Scripting (XSS) vulnerability in Joomla! CMS versions 4.0.0 through 5.4.8 and 6.0.0 through 6.1.3. The mail template feature lacks proper escaping mechanisms, allowing malicious scripts to be injected and executed in user browsers.

Detection Guidance

Check Joomla version using command: grep -r 'Joomla' /var/www/html/administrator/components/com_admin/language/en-GB/en-GB.ini | grep 'version='. If version is between 4.0.0-5.4.8 or 6.0.0-6.1.3, the system is vulnerable.

Impact Analysis

Attackers could exploit this to steal user sessions, deface websites, or deliver malware. Users viewing affected mail templates may unknowingly execute malicious scripts, compromising their data or systems.

Compliance Impact

This vulnerability could lead to unauthorized data access or breaches, violating GDPR (data protection) and HIPAA (health data privacy) requirements. Organizations may face fines or legal consequences if exploited.

Mitigation Strategies

Upgrade Joomla to version 5.4.9 or 6.1.4 immediately. If upgrading is not possible, disable the mail template feature or apply patches from Joomla's security center.

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