CVE-2022-24728 is a cross-site scripting (XSS) vulnerability identified in CKEditor4, an open-source WYSIWYG HTML editor widely used to enable rich text editing capabilities in web applications. The vulnerability resides in the core HTML processing module of CKEditor4 versions prior to 4.18.0 and affects all plugins that rely on this module. Specifically, the flaw allows an attacker to inject malformed HTML content that bypasses the editor's content sanitization mechanisms. This improper neutralization of input during web page generation (classified under CWE-79) can lead to the execution of arbitrary JavaScript code within the context of the affected web application. The exploitation does not require authentication or user interaction beyond accessing or submitting content processed by the vulnerable editor. Although no known exploits are currently reported in the wild, the vulnerability poses a significant risk because CKEditor4 is embedded in numerous web platforms, including content management systems, intranet portals, and SaaS applications. The issue was addressed and patched in version 4.18.0, but no alternative workarounds exist for earlier versions. Given the nature of XSS, successful exploitation could enable attackers to perform session hijacking, credential theft, or deliver further malicious payloads, compromising the confidentiality and integrity of user data and potentially impacting availability through subsequent attacks like defacement or malware distribution.

For European organizations, the impact of this vulnerability can be substantial, especially for those relying on CKEditor4 in customer-facing or internal web applications. Exploitation could lead to unauthorized access to sensitive information, including personal data protected under GDPR, resulting in regulatory penalties and reputational damage. Attackers could leverage the XSS flaw to conduct phishing attacks, steal session cookies, or escalate privileges within enterprise environments. Sectors such as finance, healthcare, government, and education, which often deploy CKEditor4 for content management or communication platforms, are particularly at risk. The vulnerability undermines user trust and may disrupt business operations if exploited to inject malicious scripts that alter application behavior or propagate malware. Additionally, since the vulnerability affects all plugins dependent on the core HTML processing module, the attack surface is broad, increasing the likelihood of exploitation in complex web environments prevalent in European enterprises.

European organizations should prioritize upgrading all instances of CKEditor4 to version 4.18.0 or later to apply the official patch that resolves this vulnerability. Where immediate upgrading is not feasible, organizations should implement strict input validation and output encoding on the server side to complement the editor's sanitization. Employing Content Security Policy (CSP) headers can help mitigate the impact of injected scripts by restricting the execution of unauthorized JavaScript. Regular security audits and penetration testing focused on web application components using CKEditor4 can identify residual risks. Additionally, organizations should monitor web application logs for unusual input patterns indicative of attempted XSS exploitation. For environments where CKEditor4 is embedded in third-party platforms, liaising with vendors to ensure timely patch deployment is critical. Finally, educating developers and administrators about secure coding practices and the risks of XSS vulnerabilities will help prevent similar issues in the future.