CVE-2024-5962 is a reflected cross-site scripting (XSS) vulnerability identified in the authentication endpoint of WSO2 API Manager versions 4.2.0 and 4.3.0. The root cause of this vulnerability is improper neutralization of user-supplied input during web page generation, specifically a lack of output encoding that allows malicious JavaScript code injection. When a user interacts with the vulnerable authentication endpoint, an attacker can craft a specially crafted URL or input that causes the server to reflect malicious script code back to the user's browser. This can lead to unauthorized UI modifications, redirection to attacker-controlled websites, or exfiltration of sensitive data accessible within the browser context. However, the vulnerability does not allow direct session hijacking because session cookies are protected with the httpOnly flag, which prevents JavaScript access to these cookies. The CVSS v3.1 base score of 6.1 reflects a medium severity, with an attack vector of network (remote exploitation), low attack complexity, no privileges required, but requiring user interaction (e.g., clicking a malicious link). The scope is changed, indicating that the vulnerability affects components beyond the initially vulnerable module. No known exploits in the wild have been reported yet, and no official patches have been linked at the time of this report. The vulnerability is classified under CWE-79, which covers improper neutralization of input leading to XSS attacks. Given the critical role of WSO2 API Manager in managing APIs and authentication flows, exploitation could undermine trust in authentication processes and expose users to phishing or data theft attacks via browser-based vectors.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on WSO2 API Manager for API gateway and authentication services. Successful exploitation could lead to compromised user experience through UI manipulation, phishing attacks via redirection to malicious sites, and potential leakage of sensitive information accessible in the browser context such as tokens or personal data. Although session hijacking is mitigated by httpOnly cookies, the ability to execute arbitrary scripts can still facilitate social engineering attacks or further client-side exploitation. Organizations in sectors with high regulatory scrutiny such as finance, healthcare, and government could face compliance risks if user data is exposed or if attackers leverage this vulnerability to conduct broader attacks. Additionally, the reflected nature of the XSS means that attackers can target users with crafted URLs, increasing the risk of widespread phishing campaigns. The vulnerability’s medium severity and ease of exploitation without authentication make it a credible threat vector that requires timely mitigation to prevent reputational damage and potential regulatory penalties under GDPR and other data protection laws.

To mitigate CVE-2024-5962, European organizations should: 1) Immediately review and apply any official patches or updates released by WSO2 once available. 2) Implement strict input validation and output encoding on all user-supplied data in the authentication endpoints to neutralize malicious scripts. 3) Employ Web Application Firewalls (WAFs) with custom rules to detect and block reflected XSS attack patterns targeting the authentication URLs. 4) Conduct thorough security testing, including automated and manual penetration tests focusing on the authentication flows to identify any residual XSS or related vulnerabilities. 5) Educate users and administrators about the risks of clicking untrusted links, especially those purporting to be authentication URLs. 6) Consider deploying Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers interacting with the API Manager. 7) Monitor logs and network traffic for unusual patterns indicative of attempted exploitation. 8) For organizations with custom integrations or extensions on WSO2 API Manager, review code for similar output encoding issues and remediate accordingly. These steps go beyond generic advice by focusing on both immediate protective controls and longer-term secure coding and monitoring practices tailored to the authentication context.