This indicates an attack attempt against a Cross-Site Scripting (XSS) vulnerability in Joomla! CMS.
The vulnerability is caused by inadequate input filtering of line feed character which leads to XSS vulnerabilities in various components. A remote attacker may be able to exploit this to execute arbitrary script code within the context of the application.
Joomla! 3.0.0 through 3.8.7
System Compromise : Remote attackers can execute arbitrary script code within the context of the target user's browser
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