CVE-1999-1118 is a vulnerability affecting the ndd utility in Solaris version 2.6, an operating system developed by Sun Microsystems. The ndd command is used to modify kernel network parameters, including TCP/IP settings. This vulnerability allows local users—those with access to the system—to cause a denial of service (DoS) condition by modifying certain TCP/IP parameters improperly. Specifically, by changing these parameters, an attacker can disrupt normal network stack operations, potentially causing the system's networking functionality to become unstable or unresponsive. The vulnerability does not allow unauthorized remote access, nor does it compromise confidentiality or integrity of data; its impact is limited to availability. The CVSS score of 2.1 (low severity) reflects that exploitation requires local access, has low complexity, no authentication is required beyond local user privileges, and results only in a partial loss of availability. Since Solaris 2.6 is an outdated operating system released in the late 1990s, this vulnerability is primarily of historical interest, but it remains relevant for legacy systems still in operation. No patches or fixes are available, and there are no known exploits in the wild targeting this vulnerability. The risk is therefore limited to environments where Solaris 2.6 is still used and local user access is possible.

For European organizations, the impact of this vulnerability is generally low due to the obsolescence of Solaris 2.6 in modern IT environments. However, organizations that maintain legacy systems running Solaris 2.6—such as in industrial control systems, telecommunications infrastructure, or specialized research environments—could face service disruptions if local users exploit this vulnerability. A denial of service in critical network components could lead to temporary loss of network connectivity, affecting business operations, internal communications, or access to critical applications. Since the vulnerability requires local access, the threat is mainly from insider threats or attackers who have already compromised a user account. The lack of a patch means organizations must rely on compensating controls to mitigate risk. Overall, the threat is unlikely to cause widespread damage but could degrade availability in niche legacy environments.

Given the absence of an official patch, European organizations should implement strict access controls to limit local user permissions on Solaris 2.6 systems. This includes enforcing the principle of least privilege, ensuring only trusted administrators have access to the ndd utility and network configuration commands. Monitoring and auditing local user activities can help detect any unauthorized attempts to modify TCP/IP parameters. Network segmentation should be employed to isolate legacy Solaris systems from critical production networks to contain potential DoS impacts. Where possible, organizations should plan and execute migration strategies to upgrade from Solaris 2.6 to supported, modern operating systems that receive security updates. If migration is not immediately feasible, consider deploying host-based intrusion detection systems (HIDS) to alert on suspicious changes to network parameters. Additionally, disabling or restricting the use of ndd for non-administrative users can reduce the attack surface.