CVE-2023-23491 in Quick Event Manager Plugin
Summary
by MITRE • 01/20/2023
The Quick Event Manager WordPress Plugin, version < 9.7.5, is affected by a reflected cross-site scripting vulnerability in the 'category' parameter of its 'qem_ajax_calendar' action.
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Analysis
by VulDB Data Team • 10/08/2025
The Quick Event Manager WordPress plugin presents a critical security vulnerability through a reflected cross-site scripting flaw that affects versions prior to 9.7.5. This vulnerability exists within the plugin's qem_ajax_calendar action where the category parameter fails to properly sanitize user input, creating an avenue for malicious actors to inject arbitrary script code into web pages viewed by other users. The issue stems from inadequate input validation and output encoding practices within the plugin's ajax handling mechanism, which processes calendar-related requests through the WordPress AJAX framework.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious URL containing a crafted category parameter value that includes malicious javascript code. When a victim clicks on this malicious link and the page loads, the reflected script executes in the victim's browser context, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The reflected nature of this XSS means that the malicious payload is not stored on the server but rather injected through the request parameters and immediately reflected back to the user's browser. This vulnerability specifically targets the calendar functionality of the plugin and operates within the WordPress AJAX infrastructure, making it particularly dangerous as it can bypass standard security measures that might protect against persistent XSS attacks.
The operational impact of this vulnerability extends beyond simple script execution as it can enable sophisticated attack vectors including but not limited to cookie theft through document.cookie manipulation, browser fingerprinting, and potential privilege escalation if the victim has administrative privileges. Attackers can leverage this vulnerability to gain unauthorized access to user sessions, manipulate calendar events, or even deploy more complex attacks such as phishing campaigns that appear legitimate to users. The vulnerability affects any user who interacts with the calendar functionality of the plugin, making it particularly concerning for organizations that rely heavily on event management features within their WordPress installations. The attack surface is widened by the fact that this vulnerability can be exploited through social engineering techniques where attackers convince users to click on malicious links.
Security mitigations for this vulnerability involve immediate patching to version 9.7.5 or later which includes proper input sanitization and output encoding for the category parameter. Organizations should implement comprehensive input validation at multiple layers including application-level filtering and output encoding for all dynamic content. The implementation of content security policies can provide additional protection against XSS attacks by restricting the sources from which scripts can be loaded. Regular security audits of WordPress plugins and themes should be conducted to identify similar vulnerabilities, with particular attention to AJAX handlers and user input processing functions. This vulnerability aligns with CWE-79 which describes improper neutralization of input during web page generation, and maps to ATT&CK technique T1566.001 for credential access through social engineering. System administrators should also consider implementing web application firewalls that can detect and block suspicious patterns in URL parameters, though this represents a secondary defense measure that should not replace proper code-level fixes.