CVE-2025-15021 identifies a stored cross-site scripting vulnerability in the Gotham Block Extra Light plugin for WordPress, present in all versions up to and including 1.5.0. The vulnerability stems from improper neutralization of input during web page generation, specifically within the plugin's admin settings interface. Because of insufficient input sanitization and lack of output escaping, authenticated users with administrator-level permissions or higher can inject arbitrary JavaScript code into pages. These scripts execute whenever any user accesses the compromised page, potentially leading to session hijacking, privilege escalation, or data theft. The vulnerability is constrained to WordPress multi-site installations or single-site setups where the unfiltered_html capability is disabled, limiting its scope. Exploitation requires high privileges (administrator) and no user interaction, but the attack complexity is high due to the need for admin access. The CVSS 3.1 base score is 4.4, reflecting a medium severity with low confidentiality and integrity impact and no availability impact. No public exploits have been reported yet, and no patches are currently linked, indicating the need for vendor action. The vulnerability is classified under CWE-79, a common web application security weakness related to cross-site scripting. Organizations running multi-site WordPress environments with this plugin should prioritize remediation to prevent potential script injection attacks that could compromise user trust and data integrity.

For European organizations, the impact of CVE-2025-15021 can be significant in environments where the Gotham Block Extra Light plugin is deployed on multi-site WordPress installations. Successful exploitation allows attackers with administrator privileges to inject malicious scripts that execute in the context of other users visiting the affected pages. This can lead to theft of session cookies, unauthorized actions performed on behalf of users, and potential compromise of sensitive data. Although the vulnerability requires high privileges to exploit, insider threats or compromised admin accounts could leverage this flaw to escalate attacks. The impact on confidentiality and integrity is moderate, while availability remains unaffected. Given the widespread use of WordPress in Europe, especially in sectors like media, education, and government that often use multi-site setups, this vulnerability could facilitate targeted attacks or lateral movement within networks. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits once patches are released. Organizations failing to address this vulnerability risk reputational damage, data breaches, and regulatory non-compliance under GDPR if personal data is exposed.

1. Monitor the Gothamdev vendor channels and WordPress plugin repositories for official patches addressing CVE-2025-15021 and apply them promptly upon release. 2. Until patches are available, restrict administrator-level access strictly to trusted personnel and enforce strong authentication mechanisms such as multi-factor authentication (MFA). 3. Review and harden WordPress multi-site configurations, ensuring that unfiltered_html capability is enabled only where absolutely necessary. 4. Implement web application firewalls (WAFs) with custom rules to detect and block suspicious script injection attempts targeting the plugin's admin settings. 5. Conduct regular security audits and code reviews of installed plugins to identify and remediate insecure input handling. 6. Educate administrators on the risks of XSS and the importance of cautious input handling within WordPress admin interfaces. 7. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in affected web applications. 8. Monitor logs for unusual admin activity or unexpected changes in plugin settings that could indicate exploitation attempts. These steps collectively reduce the risk of exploitation and limit potential damage from this vulnerability.