CVE-2024-8990 is a stored Cross-Site Scripting (XSS) vulnerability identified in the Geo Mashup plugin for WordPress, affecting all versions up to and including 1.13.13. The vulnerability stems from insufficient input sanitization and output escaping on user-supplied attributes passed to the geo_mashup_visible_posts_list shortcode. This flaw allows authenticated attackers with contributor-level access or higher to inject arbitrary JavaScript code into pages generated by the plugin. When other users visit these pages, the malicious scripts execute in their browsers, potentially leading to session hijacking, privilege escalation, or unauthorized actions within the context of the victim’s session. The vulnerability is exploitable remotely over the network without user interaction beyond visiting the compromised page. The CVSS v3.1 score of 6.4 reflects a medium severity, considering the attack vector is network-based, the attack complexity is low, privileges are required but no user interaction is needed, and the impact affects confidentiality and integrity but not availability. Although no known exploits are currently reported in the wild, the presence of this vulnerability in a popular WordPress plugin poses a tangible risk to websites using Geo Mashup, especially those allowing contributor-level user roles. The vulnerability highlights the importance of proper input validation and output encoding in web applications to prevent injection attacks.

The primary impact of CVE-2024-8990 is the potential compromise of user confidentiality and integrity on websites using the vulnerable Geo Mashup plugin. Attackers with contributor-level access can inject malicious scripts that execute in the browsers of site visitors, enabling theft of session cookies, user credentials, or other sensitive information. This can lead to account takeover, unauthorized actions performed on behalf of users, or further exploitation of the website. While availability is not directly affected, the reputational damage and potential data breaches can have significant operational and financial consequences. Organizations relying on WordPress sites with this plugin are at risk of targeted attacks, especially if contributor roles are assigned to untrusted users. The vulnerability could also be leveraged as a foothold for broader attacks within an organization's web infrastructure. Given WordPress's widespread use globally, the scope of affected systems is substantial, increasing the potential impact if exploited at scale.

To mitigate CVE-2024-8990, organizations should immediately update the Geo Mashup plugin to a version that addresses this vulnerability once released by the vendor. Until a patch is available, restrict contributor-level access to trusted users only and review user roles to minimize the number of users who can exploit this flaw. Implement Web Application Firewall (WAF) rules to detect and block suspicious input patterns targeting the geo_mashup_visible_posts_list shortcode parameters. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in browsers. Conduct regular security audits and code reviews of plugins, especially those handling user input in shortcodes or dynamic page elements. Educate site administrators on the risks of granting contributor-level permissions and enforce the principle of least privilege. Additionally, monitor website logs for unusual activity or injection attempts related to this plugin. Finally, consider isolating or sandboxing WordPress environments to reduce the blast radius of any successful exploitation.