CVE-2025-6290 is a stored cross-site scripting (XSS) vulnerability identified in the blakelong Tournament Bracket Generator plugin for WordPress, affecting all versions up to and including 1.0.0. The vulnerability stems from improper neutralization of input during web page generation, specifically insufficient sanitization and escaping of user-supplied attributes within the plugin's 'bracket' shortcode. This allows authenticated attackers with contributor-level privileges or higher to inject arbitrary JavaScript code into pages generated by the plugin. When other users access these pages, the injected scripts execute in their browsers, potentially leading to session hijacking, unauthorized actions, or data theft. The vulnerability has a CVSS 3.1 base score of 6.4, reflecting a medium severity level. The attack vector is network-based, with low complexity, requiring privileges equivalent to contributor access but no user interaction. The scope is changed, as the vulnerability can affect other users viewing the injected content. Confidentiality and integrity impacts are low, while availability is unaffected. No public exploits have been reported yet. The vulnerability was published on June 26, 2025, and assigned by Wordfence. The plugin's widespread use in WordPress sites that manage tournaments or competitions makes this a relevant threat for many organizations. The lack of a patch link indicates that a fix may not yet be available, emphasizing the need for interim mitigations.

The primary impact of CVE-2025-6290 is the potential for attackers with contributor-level access to inject malicious scripts that execute in the browsers of users visiting affected pages. This can lead to session hijacking, theft of sensitive information such as cookies or credentials, unauthorized actions performed on behalf of users, and possible defacement or manipulation of website content. While availability is not impacted, the compromise of confidentiality and integrity can damage organizational reputation, lead to data breaches, and facilitate further attacks such as privilege escalation or lateral movement within the network. Organizations relying on the Tournament Bracket Generator plugin, especially those with active contributor communities, face increased risk. The vulnerability's medium severity and ease of exploitation by authenticated users make it a significant concern for WordPress sites that cannot immediately patch or mitigate the issue. The scope of impact extends to all users who view the injected content, potentially affecting site visitors and administrators alike.

1. Immediately restrict contributor-level and higher user privileges to trusted individuals only, minimizing the risk of malicious script injection. 2. Implement strict input validation and sanitization on all user-supplied data related to the 'bracket' shortcode, using WordPress security functions such as wp_kses() or esc_html() to neutralize potentially dangerous content. 3. Monitor and audit content created via the Tournament Bracket Generator plugin for suspicious scripts or unexpected code. 4. Disable or remove the plugin temporarily if patching is not yet available and the risk is unacceptable. 5. Keep WordPress core and all plugins updated, and subscribe to vendor advisories for timely patch releases. 6. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts on affected pages. 7. Educate contributors about safe content creation practices and the risks of injecting untrusted code. 8. Use web application firewalls (WAFs) with rules designed to detect and block XSS payloads targeting the plugin's shortcode. 9. After patch availability, promptly apply updates to remediate the vulnerability fully.