CVE-2024-48933 is a cross-site scripting (XSS) vulnerability identified in LemonLDAP::NG, an open-source Web Single Sign-On (SSO) and access management system widely used in enterprise and governmental environments. The vulnerability exists in versions prior to 2.19.3 and arises when the userControl parameter is configured to allow special HTML characters in the username input field. This misconfiguration enables remote attackers to inject arbitrary JavaScript or HTML code into the login page. When a victim accesses a maliciously crafted login URL or submits a specially crafted username, the injected script executes in the victim’s browser context. This can lead to session hijacking, credential theft, or redirection to malicious sites, compromising user confidentiality and integrity. The vulnerability does not affect system availability and requires user interaction, such as clicking a link or submitting a form. The CVSS 3.1 score of 6.1 reflects a medium severity, with an attack vector over the network, no privileges required, low attack complexity, but requiring user interaction. No public exploits have been reported yet, but the vulnerability’s presence in authentication infrastructure makes it a notable risk. LemonLDAP::NG is commonly deployed in European public sector and enterprise environments, increasing the relevance of this vulnerability in those contexts. The vulnerability can be mitigated by upgrading LemonLDAP::NG to version 2.19.3 or later, which addresses the input sanitization issue, and by configuring userControl to disallow special HTML characters in usernames, reducing the attack surface.

For European organizations, the impact of CVE-2024-48933 can be significant, especially for those relying on LemonLDAP::NG for authentication and access management. Successful exploitation could allow attackers to perform XSS attacks on login pages, leading to session hijacking, theft of authentication tokens, or phishing attacks that compromise user credentials. This undermines the confidentiality and integrity of user sessions and potentially grants unauthorized access to sensitive systems. Public sector entities, universities, and enterprises using LemonLDAP::NG for single sign-on are particularly at risk, as compromise could cascade into broader network access. While availability is not directly affected, the reputational damage and potential regulatory consequences under GDPR for data breaches could be substantial. The requirement for user interaction limits automated exploitation but does not eliminate risk, as phishing campaigns could be used to lure users into triggering the vulnerability. The absence of known exploits in the wild suggests a window for proactive mitigation before widespread attacks occur.

1. Upgrade LemonLDAP::NG to version 2.19.3 or later immediately, as this version includes the fix for the XSS vulnerability. 2. Review and harden the userControl configuration to disallow special HTML characters in usernames, preventing injection vectors. 3. Implement Content Security Policy (CSP) headers on the login page to restrict the execution of unauthorized scripts. 4. Conduct security awareness training for users to recognize and avoid phishing attempts that could exploit this vulnerability. 5. Monitor web server and application logs for suspicious input patterns or unusual login page requests that could indicate attempted exploitation. 6. Employ web application firewalls (WAF) with rules targeting XSS payloads to provide an additional layer of defense. 7. Regularly audit and test authentication interfaces for injection vulnerabilities as part of a secure development lifecycle. 8. Coordinate with LemonLDAP::NG community and security mailing lists to stay informed about patches and emerging threats.