CVE-2024-23659 is a cross-site scripting (XSS) vulnerability affecting SPIP, an open-source content management system widely used for website publishing. The vulnerability exists in versions prior to 4.1.14 and 4.2.x prior to 4.2.8. It arises due to insufficient sanitization of the name of an uploaded file, specifically related to the JavaScript files javascript/bigup.js and javascript/bigup.utils.js. An attacker can craft a malicious file name containing executable JavaScript code that, when processed by the vulnerable SPIP instance, is executed in the context of the victim's browser. This vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation), which is a common vector for XSS attacks. The CVSS v3.1 base score is 6.1 (medium severity), with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but requiring user interaction (UI:R). The scope is changed (S:C), indicating that the vulnerability can affect components beyond the initially vulnerable component. The impact affects confidentiality and integrity (C:L/I:L) but not availability (A:N). There are no known exploits in the wild at the time of publication, and no official patches or vendor project details were provided in the source information. The vulnerability allows an attacker to execute arbitrary scripts in the context of the user's browser session, potentially leading to session hijacking, defacement, or redirection to malicious sites. Given the nature of SPIP as a CMS, this can compromise website visitors and administrators alike if exploited.

For European organizations using SPIP as their content management system, this vulnerability poses a significant risk to website security and user trust. Exploitation could lead to theft of session cookies, enabling attackers to impersonate legitimate users or administrators, potentially leading to unauthorized access or content manipulation. This can damage the organization's reputation, result in data breaches involving personal data protected under GDPR, and cause operational disruptions. Since SPIP is often used by public institutions, media outlets, and educational organizations in Europe, the impact could extend to critical public-facing services. The requirement for user interaction means that phishing or social engineering could be used to trigger the exploit, increasing the risk to end users. Although no known exploits are currently reported, the medium CVSS score and the nature of XSS vulnerabilities suggest that attackers may develop exploits, especially targeting less frequently updated SPIP installations. The confidentiality and integrity impacts, combined with the changed scope, indicate that the vulnerability could affect multiple components or user roles within an organization’s web infrastructure.

European organizations should immediately verify their SPIP version and upgrade to at least 4.1.14 or 4.2.8 where this vulnerability is addressed. If upgrading is not immediately possible, organizations should implement strict input validation and sanitization on file upload names, ensuring that any special characters or scripts are neutralized before processing or rendering. Web application firewalls (WAFs) can be configured to detect and block suspicious payloads in file names or HTTP requests targeting the vulnerable endpoints (javascript/bigup.js and javascript/bigup.utils.js). Additionally, organizations should enforce Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in the browser context, mitigating the impact of potential XSS payloads. User awareness training to recognize phishing attempts that could trigger the vulnerability is also recommended. Regular security audits and penetration testing focused on web application vulnerabilities should be conducted to detect any residual or related issues. Finally, monitoring web logs for unusual file upload patterns or script injection attempts can provide early warning of exploitation attempts.