CVE-2024-0664 is a medium-severity stored Cross-Site Scripting (XSS) vulnerability affecting the Meks Smart Social Widget WordPress plugin, versions up to and including 1.6.3. This vulnerability arises from improper input sanitization and output escaping during web page generation, classified under CWE-79. Specifically, authenticated attackers with administrator-level privileges on WordPress multi-site installations or on single-site installations where the 'unfiltered_html' capability is disabled can inject arbitrary malicious scripts into pages via the vulnerable widget. These injected scripts execute in the context of any user who visits the compromised page, potentially leading to session hijacking, privilege escalation, or other malicious activities. The vulnerability requires high privileges (administrator) and does not require user interaction to trigger once the malicious script is injected. The CVSS 3.1 base score is 4.4, reflecting a network attack vector with high attack complexity and privileges required, causing limited confidentiality and integrity impacts but no availability impact. No known exploits are currently reported in the wild, and no official patches have been linked yet. The vulnerability is scoped to multi-site WordPress environments or those with restricted HTML filtering, limiting its exposure to specific configurations rather than all installations of the plugin.

For European organizations, the impact of this vulnerability can be significant in environments using WordPress multi-site setups with the Meks Smart Social Widget plugin. Organizations relying on WordPress for corporate websites, intranets, or customer portals could face risks of unauthorized script execution leading to data leakage, session hijacking, or defacement. The requirement for administrator-level access reduces the risk of external attackers exploiting this vulnerability directly; however, insider threats or compromised admin credentials could enable exploitation. The vulnerability's ability to affect multi-site installations is particularly concerning for large organizations or service providers managing multiple WordPress sites under one installation, as a single injection could affect multiple sites and users. Given the widespread use of WordPress in Europe across various sectors, including government, education, and commerce, exploitation could undermine trust, cause reputational damage, and lead to compliance issues under GDPR if personal data is exposed. The lack of known exploits reduces immediate risk but does not eliminate the need for proactive mitigation.

1. Immediate mitigation should include auditing WordPress installations to identify multi-site setups using the Meks Smart Social Widget plugin, especially versions up to 1.6.3. 2. Restrict administrator access strictly and enforce strong authentication mechanisms such as multi-factor authentication to reduce the risk of credential compromise. 3. Temporarily disable or remove the Meks Smart Social Widget plugin in multi-site environments until a patch is available. 4. Review and harden WordPress security configurations, particularly the 'unfiltered_html' capability, to prevent unauthorized HTML/script injection by lower-privileged users. 5. Monitor logs and user activity for suspicious administrator actions or unexpected content changes in widget areas. 6. Once a vendor patch is released, promptly apply updates and verify the fix in a staging environment before production deployment. 7. Educate administrators about the risks of XSS and the importance of cautious plugin management. 8. Consider implementing Content Security Policy (CSP) headers to mitigate the impact of potential XSS attacks by restricting script execution sources.