CVE-2025-63059 is a stored cross-site scripting (XSS) vulnerability identified in the arscode Ninja Popups WordPress plugin, affecting all versions up to and including 4.7.8. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, allowing attackers to inject malicious JavaScript code that is stored persistently within the application. When other users or administrators access the affected pages, the malicious script executes in their browsers within the context of the vulnerable site. This can lead to session hijacking, theft of sensitive information such as cookies or credentials, unauthorized actions on behalf of users, or redirection to malicious websites. The vulnerability does not require user interaction beyond visiting the compromised page, and no authentication is necessary to exploit it, increasing its risk profile. Although no public exploits have been reported yet, the stored XSS nature makes it a critical concern for websites relying on Ninja Popups for user engagement or marketing. The lack of an available patch at the time of publication necessitates immediate attention to alternative mitigations. The vulnerability is particularly relevant for WordPress sites that use Ninja Popups to display interactive popups, as these are common attack vectors for injecting malicious content. The plugin’s widespread use in marketing and e-commerce sectors increases the potential attack surface. The vulnerability was reserved in late October 2025 and published in December 2025, indicating recent discovery and disclosure. No CVSS score has been assigned yet, but the technical details and impact suggest a high severity level.

For European organizations, the impact of CVE-2025-63059 can be significant. Stored XSS vulnerabilities enable attackers to compromise the confidentiality and integrity of user data by stealing session cookies or credentials, potentially leading to account takeover. This can also result in defacement of websites, damaging brand reputation and customer trust. For e-commerce and financial services sectors, such breaches can lead to financial losses and regulatory penalties under GDPR due to inadequate protection of personal data. The availability of the affected plugin in many WordPress sites across Europe means that a large number of organizations could be exposed, especially those relying on Ninja Popups for marketing or user engagement. Attackers could leverage this vulnerability to deliver malware or phishing content, increasing the risk of broader compromise. The absence of known exploits currently provides a window for mitigation, but the potential for automated exploitation exists once proof-of-concept code becomes available. The impact is amplified in sectors with high web traffic and sensitive user interactions, such as retail, healthcare, and government services.

Organizations should immediately inventory their WordPress installations to identify the presence of the Ninja Popups plugin and verify the version in use. Until an official patch is released, implement strict input validation and sanitization on all user inputs related to the plugin’s popup content. Deploy a robust Content Security Policy (CSP) that restricts the execution of inline scripts and limits sources of executable code to trusted domains. Use Web Application Firewalls (WAFs) with custom rules to detect and block typical XSS payloads targeting Ninja Popups. Monitor web server and application logs for unusual or suspicious activity indicative of exploitation attempts. Educate administrators and users about the risks of clicking on suspicious links or popups. Once a patch is available, prioritize immediate update of the plugin to the fixed version. Additionally, consider isolating or disabling the plugin temporarily if it is not critical to operations. Regularly back up website data and configurations to enable rapid recovery in case of compromise.