CVE-2025-10165 is a Stored Cross-Site Scripting (XSS) vulnerability identified in the AP Background plugin for WordPress, developed by hovanesvn. This vulnerability affects all versions up to and including 3.8.2. The root cause is insufficient input sanitization and output escaping on user-supplied attributes within the plugin's 'adv_parallax_back' shortcode. Specifically, authenticated users with contributor-level access or higher can inject arbitrary JavaScript code into pages via this shortcode. When other users access these compromised pages, the injected scripts execute in their browsers, potentially leading to session hijacking, privilege escalation, or redirection to malicious sites. The vulnerability is classified under CWE-79, which pertains to improper neutralization of input during web page generation. The CVSS v3.1 base score is 6.4, indicating a medium severity level. The vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N) reveals that the attack can be executed remotely over the network without user interaction, requires low attack complexity, and needs privileges equivalent to contributor-level access. The scope is changed, meaning the vulnerability affects components beyond the initially vulnerable component, and it impacts confidentiality and integrity but not availability. No known exploits are currently reported in the wild, and no patches have been linked yet. This vulnerability is significant because WordPress is widely used for website content management, and plugins like AP Background are common for enhancing visual effects. The ability for lower-privileged users to inject persistent scripts can lead to widespread compromise of site visitors and administrators.

For European organizations, this vulnerability poses a moderate risk, especially for those relying on WordPress sites with the AP Background plugin installed. Exploitation could lead to unauthorized disclosure of sensitive information (confidentiality impact) and modification of site content or user sessions (integrity impact). Since the attack requires contributor-level access, insider threats or compromised contributor accounts are the primary vectors. The persistent nature of stored XSS means that any visitor or administrator accessing the infected pages could be affected, potentially leading to credential theft or further compromise. This could damage the organization's reputation, lead to regulatory non-compliance under GDPR due to data breaches, and disrupt business operations. Organizations in sectors with high web presence, such as e-commerce, media, and public services, are particularly at risk. The lack of a patch increases the urgency for mitigation. However, the absence of known active exploits reduces immediate widespread impact but does not eliminate the risk of targeted attacks.

European organizations should take immediate steps to mitigate this vulnerability. First, audit all WordPress installations to identify the presence of the AP Background plugin and its version. If the plugin is installed, restrict contributor-level access strictly to trusted users and review user roles to minimize unnecessary privileges. Implement Web Application Firewalls (WAFs) with rules to detect and block malicious script injections targeting the 'adv_parallax_back' shortcode parameters. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts on affected sites. Monitor logs for unusual activity or script injection attempts. Until an official patch is released, consider disabling or removing the AP Background plugin if it is not critical to site functionality. Educate content contributors about safe input practices and the risks of injecting untrusted content. Regularly update WordPress core and plugins to the latest versions once patches become available. Additionally, conduct penetration testing focused on XSS vectors to identify any residual vulnerabilities.