CVE-2024-5953 is a denial of service vulnerability identified in the 389-ds-base LDAP server, a widely used open-source LDAP server implementation primarily on Linux systems. The flaw arises from improper validation of consistency within input, specifically when an authenticated user attempts to log in using a user account that has a malformed password hash. This malformed hash triggers a failure in the server's login processing logic, causing the LDAP server to crash or become unresponsive, resulting in denial of service (DoS). The vulnerability requires the attacker to have valid authentication credentials, meaning it cannot be exploited by unauthenticated users. No user interaction beyond the login attempt is necessary. The CVSS 3.1 base score is 5.7 (medium severity), reflecting the limited scope of impact (availability only), the requirement for authentication, and the ease of exploitation given valid credentials. There are no known exploits in the wild at the time of publication, and no patches have been linked yet, though vendors such as Red Hat are expected to release fixes. The vulnerability affects the availability of LDAP services, which are critical for authentication and directory services in many enterprise environments. This could lead to service outages, impacting user authentication and access to network resources.

For European organizations, the primary impact of CVE-2024-5953 is the potential disruption of authentication services due to LDAP server crashes. Many enterprises, government agencies, and critical infrastructure providers in Europe rely on LDAP for centralized authentication and directory services. A denial of service on these servers could lead to widespread access issues, interrupting business operations and potentially delaying critical services. While the vulnerability does not expose sensitive data or allow privilege escalation, the loss of availability can have significant operational consequences. Organizations with large-scale deployments of 389-ds-base LDAP servers, especially in sectors like finance, healthcare, and public administration, may experience increased risk. Additionally, the requirement for authentication means insider threats or compromised credentials could be leveraged to exploit this vulnerability. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as patches are not yet available.

To mitigate CVE-2024-5953, organizations should first monitor and restrict access to LDAP servers to trusted and authenticated users only, minimizing the attack surface. Implement strict credential management and monitoring to detect anomalous login attempts, particularly those involving malformed password hashes. Network segmentation and firewall rules should limit LDAP access to necessary systems and users. Once vendor patches or updates are released, they should be applied promptly to address the underlying input validation flaw. In the interim, consider deploying LDAP service redundancy and failover mechanisms to reduce the impact of potential DoS events. Logging and alerting on LDAP authentication failures can provide early warning of exploitation attempts. Additionally, review and harden authentication policies to prevent the creation or use of malformed password hashes. Engage with vendors or community support channels for updates and recommended configurations.