CVE-2024-9866 is a stored Cross-Site Scripting vulnerability classified under CWE-79 affecting the 'Event Tickets with Ticket Scanner' WordPress plugin developed by sasonikolov. The vulnerability exists in all versions up to and including 2.4.4 due to insufficient input sanitization and output escaping of the 'data' parameters used during web page generation. Additionally, earlier versions had missing authorization controls on ticket management functionality, allowing authenticated users with minimal privileges (subscriber-level and above) to inject arbitrary JavaScript code. This malicious code is stored persistently and executes whenever any user accesses the compromised page, potentially leading to session hijacking, credential theft, or unauthorized actions performed in the context of the victim's browser. The authorization flaw was addressed in version 2.4.1, while the XSS vulnerability was fully remediated in version 2.4.4. The vulnerability requires an attacker to have authenticated access and user interaction (visiting the infected page) to trigger the exploit. The CVSS 3.1 score of 5.4 reflects a medium severity, with network attack vector, low attack complexity, requiring privileges and user interaction, and impacts on confidentiality and integrity but no availability impact. No public exploits have been reported yet, but the widespread use of WordPress and this plugin in event management contexts makes timely patching critical.

The primary impact of CVE-2024-9866 is the potential for attackers with subscriber-level access to inject persistent malicious scripts into web pages generated by the vulnerable plugin. This can lead to session hijacking, theft of sensitive user data, unauthorized actions performed on behalf of users, and potentially the spread of malware or phishing attacks through trusted sites. Since the vulnerability affects a WordPress plugin commonly used for event ticketing, organizations relying on this plugin risk compromising the confidentiality and integrity of their users' data and interactions. The attack requires authenticated access, which limits exposure to some extent, but subscriber-level privileges are common in many WordPress sites, increasing the attack surface. The missing authorization in earlier versions also allowed unauthorized ticket management actions, which could disrupt event operations or lead to fraudulent ticket issuance. Although no availability impact is noted, reputational damage and loss of user trust could be significant. Organizations worldwide using this plugin, especially those managing large user bases or sensitive event data, face increased risk until patched.

Organizations should immediately upgrade the 'Event Tickets with Ticket Scanner' plugin to version 2.4.4 or later, where both the authorization and XSS issues are fully patched. Until upgrading, restrict subscriber-level user capabilities to minimize the risk of script injection. Implement Web Application Firewall (WAF) rules to detect and block suspicious input patterns targeting the 'data' parameters of the plugin. Conduct thorough audits of existing ticket management pages and user-generated content for signs of injected scripts. Enforce the principle of least privilege by reviewing and limiting user roles and permissions in WordPress, especially for subscriber-level accounts. Enable Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. Regularly monitor logs and user activity for anomalous behavior indicative of exploitation attempts. Educate site administrators and users about the risks of XSS and the importance of timely updates. Finally, maintain a robust backup and incident response plan to recover quickly if exploitation occurs.