CVE-2025-6690 is a stored Cross-Site Scripting (XSS) vulnerability identified in the WP Tournament Registration plugin for WordPress, developed by archaeopath. This vulnerability affects all versions up to and including 1.3.0. The root cause is improper neutralization of input during web page generation, specifically insufficient sanitization and output escaping of the 'field' parameter. An authenticated attacker with Contributor-level access or higher can exploit this flaw by injecting arbitrary malicious scripts into pages generated by the plugin. These scripts are stored persistently and executed whenever any user accesses the compromised page, potentially leading to session hijacking, privilege escalation, or redirection to malicious sites. The vulnerability has a CVSS v3.1 base score of 6.4, indicating a medium severity level. The attack vector is network-based (remote), requires low attack complexity, and privileges at the contributor level, but does not require user interaction. The scope is changed, meaning the vulnerability can affect components beyond the initially vulnerable plugin, potentially impacting the entire WordPress site. Confidentiality and integrity are impacted to a limited extent, while availability is not affected. No known exploits are currently reported in the wild, and no official patches have been released yet. The vulnerability was reserved in late June 2025 and published in early August 2025.

For European organizations using WordPress sites with the WP Tournament Registration plugin, this vulnerability poses a tangible risk of persistent XSS attacks. Attackers with contributor-level access—often achievable through compromised accounts or weak internal controls—can inject malicious scripts that execute in the context of site visitors or administrators. This can lead to theft of authentication cookies, unauthorized actions performed on behalf of users, defacement, or distribution of malware. Organizations involved in sports, event management, or community engagement using this plugin may face reputational damage, data breaches, and regulatory scrutiny under GDPR if personal data is compromised. The medium severity score reflects that while the vulnerability does not directly affect availability, the confidentiality and integrity of user data and site content can be undermined. Additionally, the changed scope indicates potential wider impact on the WordPress environment, increasing the risk to integrated systems or plugins. The absence of known exploits suggests a window for proactive mitigation, but also the need for vigilance as attackers may develop exploits rapidly.

European organizations should immediately audit their WordPress installations to identify the presence of the WP Tournament Registration plugin, especially versions up to 1.3.0. Until an official patch is released, organizations should implement the following measures: 1) Restrict Contributor-level access strictly to trusted users and review user roles and permissions to minimize exposure. 2) Employ Web Application Firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting the 'field' parameter in plugin requests. 3) Enable Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in browsers. 4) Conduct manual code reviews or apply temporary input sanitization and output escaping patches if feasible. 5) Monitor logs for unusual activities related to the plugin, including unexpected POST requests or script injections. 6) Educate site administrators and users about phishing and social engineering risks that could lead to account compromise. Once the vendor releases a patch, prioritize immediate update and verify the fix. Additionally, consider isolating the plugin or disabling it temporarily if it is not critical to operations.