CVE-2024-11831 is a cross-site scripting vulnerability found in the npm package serialize-javascript version 6.0. The vulnerability stems from improper neutralization of input during web page generation, specifically the failure to sanitize certain JavaScript inputs such as regular expressions or complex object types. When these inputs are serialized and sent to a web client, malicious code can be injected and executed in the victim's browser context upon deserialization. This leads to potential XSS attacks that can compromise the confidentiality and integrity of user data and application state. The vulnerability requires an attacker to have some level of privileges (PR:L) and user interaction (UI:R) to trigger the exploit, with network attack vector (AV:N) and low attack complexity (AC:L). The scope is changed (S:C), meaning the vulnerability can affect resources beyond the initially vulnerable component. The CVSS v3.1 base score is 5.4, indicating a medium severity level. No public exploits are currently known, but the vulnerability is critical in environments where serialized data is dynamically generated and sent to clients, such as single-page applications or server-side rendered apps using this package. The issue highlights the risks of improper input sanitization in serialization libraries widely used in JavaScript ecosystems.

For European organizations, this vulnerability poses a risk primarily to web applications that utilize the serialize-javascript package version 6.0 to serialize data sent to clients. Exploitation could lead to XSS attacks, allowing attackers to execute arbitrary scripts in users' browsers, potentially stealing session tokens, manipulating DOM content, or performing actions on behalf of users. This can result in data breaches, loss of user trust, and regulatory non-compliance under GDPR if personal data is exposed. The impact is heightened for organizations with public-facing web services, e-commerce platforms, or critical infrastructure portals. Since the vulnerability requires some privilege and user interaction, internal applications with authenticated users are also at risk. The medium severity score reflects that while the vulnerability is exploitable, it is not trivially so, but the widespread use of the package increases the attack surface. European sectors such as finance, healthcare, and government services that rely on modern JavaScript frameworks could be particularly vulnerable.

1. Upgrade serialize-javascript to a patched version as soon as it becomes available from the maintainers. Monitor official repositories and advisories for updates. 2. Implement strict input validation and sanitization on all data before serialization, especially for user-supplied inputs that may include regex or complex objects. 3. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers, mitigating the impact of potential XSS attacks. 4. Conduct thorough code reviews and security testing focusing on serialization and deserialization logic in web applications. 5. Use security-focused static analysis tools to detect unsafe serialization patterns. 6. Educate developers on secure coding practices related to serialization and client-side data handling. 7. Where feasible, avoid sending serialized JavaScript objects that include executable code or complex types to clients. 8. Monitor web application logs and user reports for signs of XSS exploitation attempts.