CVE-2025-11856 is a stored Cross-Site Scripting (XSS) vulnerability identified in the Eventbee Ticketing Widget plugin for WordPress, which is widely used for managing event ticket sales and registrations. The vulnerability exists due to improper neutralization of input during web page generation, specifically in the 'eventbeeticketwidget' shortcode. This shortcode fails to properly sanitize and encode several parameters, allowing authenticated users with contributor-level privileges or higher to inject arbitrary JavaScript code into pages. Because the malicious script is stored persistently, it executes every time any user accesses the infected page, potentially compromising user sessions, stealing cookies, or performing unauthorized actions on behalf of users. The vulnerability is exploitable remotely over the network without user interaction, with low attack complexity, but requires at least contributor-level authentication, limiting exposure to some extent. The CVSS 3.1 score of 6.4 reflects a medium severity, indicating a significant but not critical risk. No patches or fixes are currently linked, and no known active exploits have been reported. The vulnerability affects all versions up to and including 1.0 of the plugin, which suggests that users should verify their plugin version and apply updates or mitigations once available. The CWE-79 classification highlights the core issue as improper input sanitization leading to XSS. Given the plugin’s role in event ticketing, exploitation could disrupt event operations or compromise attendee data. The vulnerability’s scope includes all websites using this plugin, especially those with multiple contributors managing content. The persistent nature of the XSS increases the risk of widespread impact once exploited.

For European organizations, this vulnerability could lead to unauthorized script execution on websites that use the Eventbee Ticketing Widget plugin, potentially compromising the confidentiality and integrity of user data such as session tokens and personal information. Attackers could hijack user sessions, deface event pages, or redirect users to malicious sites, damaging organizational reputation and trust. Event management companies, cultural institutions, and businesses relying on online ticket sales are particularly at risk, as disruption or data compromise could impact revenue and customer relationships. The requirement for contributor-level access reduces the risk from external anonymous attackers but raises concerns about insider threats or compromised accounts. The vulnerability does not affect availability directly but could lead to indirect denial of service through site defacement or loss of user trust. Given the widespread use of WordPress in Europe and the popularity of event ticketing solutions, the potential impact is moderate to high, especially for organizations with multiple content contributors and high web traffic. The lack of known exploits in the wild currently limits immediate risk but also underscores the need for proactive mitigation.

European organizations should immediately audit their WordPress installations to identify the presence of the Eventbee Ticketing Widget plugin and verify the version in use. Until an official patch is released, administrators should consider disabling the plugin or removing the vulnerable shortcode from all pages. Restrict contributor-level access strictly to trusted users and implement multi-factor authentication to reduce the risk of account compromise. Employ Web Application Firewalls (WAFs) with custom rules to detect and block suspicious input patterns related to the vulnerable shortcode parameters. Sanitize and validate all user inputs rigorously at the application level as a defense-in-depth measure. Monitor website logs and user activity for signs of unusual script injections or unauthorized changes. Educate content contributors about the risks of injecting untrusted content and enforce strict content policies. Once a patch becomes available, prioritize its deployment and conduct thorough testing to ensure the vulnerability is fully remediated. Additionally, consider implementing Content Security Policy (CSP) headers to limit the impact of potential XSS attacks by restricting script execution sources.