CVE-2026-25016 identifies a missing authorization vulnerability in the Nelio Popups plugin developed by Nelio Software, affecting versions up to and including 1.3.5. This vulnerability arises from improperly configured access control security levels, which fail to enforce authorization checks on certain plugin functionalities. As a result, an attacker can exploit this flaw to perform unauthorized actions within the plugin context, such as modifying popup settings, injecting malicious content, or accessing restricted administrative features. The vulnerability does not require prior authentication, increasing its risk profile, and does not depend on user interaction, making automated exploitation feasible. Nelio Popups is a WordPress plugin widely used for managing popups on websites, which means the attack surface includes any WordPress site running the affected versions. Although no public exploits or patches are currently available, the vulnerability's presence in a popular plugin used for marketing and user engagement presents a significant risk. The lack of a CVSS score necessitates an assessment based on the potential impact on confidentiality, integrity, and availability, as well as exploitation complexity and scope.

For European organizations, this vulnerability could lead to unauthorized modification of website popups, potentially enabling phishing, malware distribution, or unauthorized data collection through manipulated user interactions. The integrity of marketing campaigns and user trust could be compromised, affecting brand reputation and customer relationships. Confidential information collected via popups, such as email addresses or personal data, might be exposed or altered. The availability of popup functionality could be disrupted, impacting user experience and conversion rates. Organizations in sectors relying heavily on digital marketing, e-commerce, or customer engagement platforms are particularly vulnerable. Additionally, regulatory compliance risks arise under GDPR if personal data is mishandled due to exploitation. The absence of known exploits currently limits immediate impact but does not diminish the urgency for mitigation given the ease of exploitation and potential consequences.

Organizations should monitor Nelio Software announcements for official patches and apply them promptly once released. Until patches are available, restrict access to WordPress administrative interfaces to trusted personnel only and enforce strong authentication mechanisms such as multi-factor authentication. Review and tighten user roles and permissions within WordPress to minimize exposure. Implement web application firewalls (WAFs) with rules designed to detect and block unauthorized attempts to access or modify popup configurations. Conduct regular security audits and monitor logs for unusual activities related to the Nelio Popups plugin. Consider temporarily disabling the plugin if it is not essential or if risk tolerance is low. Educate website administrators about the risks of missing authorization vulnerabilities and encourage best practices for plugin management and updates.