CVE-2025-58861 is a high-severity vulnerability affecting the WordPress plugin 'Quick Event Calendar' developed by WP Corner. The vulnerability is classified as a Cross-Site Request Forgery (CSRF) issue (CWE-352) that enables an attacker to perform unauthorized actions on behalf of an authenticated user. Specifically, this CSRF vulnerability allows an attacker to inject stored Cross-Site Scripting (XSS) payloads into the plugin's event calendar functionality. The affected versions include all versions up to and including 1.4.9. The CVSS 3.1 base score is 7.1, indicating a high severity with the vector AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L, meaning the attack can be launched remotely over the network without privileges but requires user interaction. The scope is changed, and the impact affects confidentiality, integrity, and availability to a limited extent. The vulnerability arises because the plugin does not properly verify the authenticity of requests modifying calendar events, allowing attackers to craft malicious requests that, when executed by an authenticated user, result in stored XSS. This stored XSS can lead to session hijacking, privilege escalation, or further exploitation within the WordPress environment. No patches or fixes are currently linked, and no known exploits are reported in the wild as of the publication date.

For European organizations using WordPress sites with the Quick Event Calendar plugin, this vulnerability poses a significant risk. Attackers can exploit the CSRF to inject malicious scripts that persist in the calendar data, potentially compromising site administrators or users who interact with the calendar. This can lead to unauthorized access, data leakage, or manipulation of event data, impacting the integrity and availability of web services. Organizations in sectors such as government, finance, education, and healthcare that rely on WordPress for public-facing or internal event management could face reputational damage, regulatory non-compliance (e.g., GDPR breaches due to data exposure), and operational disruptions. Since the attack requires user interaction (e.g., an authenticated user visiting a malicious link), phishing or social engineering campaigns could be used to facilitate exploitation. The lack of patches increases the window of exposure, making timely mitigation critical.

European organizations should immediately audit their WordPress installations to identify if the Quick Event Calendar plugin is in use and verify the version. Until an official patch is released, mitigation should include disabling or uninstalling the plugin to eliminate the attack vector. Implementing Web Application Firewall (WAF) rules to detect and block suspicious CSRF attempts and XSS payloads targeting calendar endpoints can reduce risk. Enforce strict Content Security Policy (CSP) headers to limit the impact of any injected scripts. Educate users and administrators about phishing risks and the importance of not clicking on untrusted links while authenticated. Additionally, ensure that WordPress core and all plugins are kept up to date and monitor security advisories from WP Corner and Patchstack for forthcoming patches. Employing multi-factor authentication (MFA) can also reduce the risk of session hijacking resulting from XSS exploitation.