CVE-2025-39372 is a high-severity reflected Cross-site Scripting (XSS) vulnerability affecting the elbisnero WordPress Events Calendar Registration & Tickets plugin, specifically versions up to 2.6.0. The vulnerability arises from improper neutralization of user-supplied input during web page generation, classified under CWE-79. This flaw allows an attacker to inject malicious scripts into web pages viewed by other users. Because the vulnerability is reflected XSS, the malicious payload is embedded in a crafted URL or request and executed when a victim accesses that URL, without requiring stored data manipulation. The CVSS 3.1 base score of 7.1 reflects the vulnerability's characteristics: it can be exploited remotely over the network (AV:N), requires no privileges (PR:N), but does require user interaction (UI:R) such as clicking a malicious link. The scope is changed (S:C), indicating that exploitation can affect resources beyond the vulnerable component. The impact includes low confidentiality and integrity loss, and low availability impact, as attackers can execute arbitrary scripts in the context of the victim's browser, potentially stealing session tokens, performing actions on behalf of the user, or redirecting to malicious sites. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability was reserved in April 2025 and published in May 2025, indicating recent discovery. The plugin is widely used for event management on WordPress sites, which often handle registrations and ticketing, making the vulnerability particularly sensitive as it can affect user data and trust.

For European organizations, especially those relying on WordPress for event management and ticketing, this vulnerability poses a significant risk. Attackers can exploit the reflected XSS to hijack user sessions, steal credentials, or conduct phishing attacks by injecting malicious scripts into URLs shared with users. This can lead to unauthorized access to user accounts, data leakage, and reputational damage. Organizations handling personal data under GDPR must be cautious, as exploitation could result in data breaches with regulatory consequences. Additionally, event-related websites often have high traffic and user engagement, increasing the likelihood of successful exploitation. The reflected nature means attackers can craft targeted phishing campaigns to European users, potentially impacting sectors such as education, cultural institutions, and corporate event organizers. The vulnerability's ability to affect integrity and availability, albeit low, could disrupt event registration processes, causing operational issues.

European organizations should immediately audit their WordPress installations to identify if the elbisnero Events Calendar Registration & Tickets plugin is in use and confirm the version. Until an official patch is released, mitigation can include disabling or removing the plugin to eliminate exposure. Implementing Web Application Firewalls (WAFs) with custom rules to detect and block suspicious input patterns related to the plugin's endpoints can reduce risk. Organizations should also educate users about the dangers of clicking untrusted links and encourage the use of browser security features that block script execution from untrusted sources. Monitoring web server logs for unusual query parameters or repeated suspicious requests targeting the plugin can help detect exploitation attempts. Once a patch is available, prompt application of updates is critical. Additionally, employing Content Security Policy (CSP) headers can mitigate the impact of XSS by restricting script execution contexts. Regular security assessments and penetration testing focusing on plugin vulnerabilities should be integrated into the security lifecycle.