The Joomla! Framework Filter package contains an XSS vulnerability (CWE-79) due to insufficient filtering in the checkAttribute methods. This flaw affects multiple versions of the package (1.0.0-3.0.5 and 4.0.0-4.0.1) and can lead to improper neutralization of input during web page generation, potentially enabling injection of malicious scripts. The vulnerability is rated medium severity with a CVSS 4.0 score of 6.9. No vendor advisory or patch information is currently available, and no known exploitation has been reported.

Successful exploitation could allow an attacker with high privileges and partial user interaction to inject malicious scripts into web pages generated by affected Joomla! Framework components. This may lead to limited integrity and availability impacts as indicated by the CVSS vector, but the overall severity is medium. No evidence of active exploitation is reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, users should monitor Joomla! Project communications for updates. No specific temporary mitigations are documented at this time.