XSS Vulnerability in Joomla! Core Affecting Multiple Versions
CVE-2026-90918

6.9MEDIUM

Key Information:

Vendor

Joomla
Status
Joomla! Cms
Vendor
CVE Published:
29 September 2026

What is CVE-2026-90918?

A security flaw exists within the HTML mail template feature of Joomla! Core, where the absence of an adequate escaping mechanism enables potential Cross-Site Scripting (XSS) attacks. This vulnerability affects several versions from Joomla 4.0.0 to Joomla 6.1.3, allowing malicious actors to inject harmful scripts through crafted emails, compromising user data and site integrity across affected installations. It is crucial for Joomla users to review the affected versions and implement necessary updates to mitigate associated risks.

Affected Version(s)

Joomla! CMS 4.0.0-5.4.8

Joomla! CMS 6.0.0-6.1.3

References

https://www.joomla.org/
product
https://developer.joomla.org/security-centre/1088-2026090...
vendor-advisory

CVSS V4

Score:
6.9
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Joe Grey / GitHub @StressTestor
Joe Grey / GitHub @StressTestor
.