CVE-1999-0485 is a vulnerability identified in OpenBSD version 2.4, specifically within the ipintr() function in the ipq component. This vulnerability allows remote attackers to cause a system crash, effectively resulting in a denial-of-service (DoS) condition. The issue lies in the handling of IP packets within the ipq (IP queue) subsystem, where crafted network traffic can trigger a fault in the ipintr() function, leading to system instability or crash. Since this vulnerability dates back to 1999 and affects an outdated OpenBSD version, it reflects a historical security flaw rather than a contemporary threat. The CVSS score of 2.6 (low severity) indicates that while the vulnerability can impact system availability, it requires high attack complexity and does not affect confidentiality or integrity. There is no authentication required to exploit this vulnerability, but the attacker must be able to send specially crafted packets to the target system over the network. No patches are available for this specific version, and there are no known exploits in the wild documented. Given the age of the vulnerability and the obsolescence of OpenBSD 2.4, modern systems are unlikely to be affected unless legacy systems remain in operation.

For European organizations, the impact of CVE-1999-0485 is generally minimal due to the obsolescence of OpenBSD 2.4 in production environments. However, if legacy systems running this version are still in use—such as in specialized or embedded environments—there is a risk of denial-of-service attacks that can disrupt network services or critical infrastructure components relying on these systems. The vulnerability does not compromise data confidentiality or integrity but can cause service outages, which may affect business continuity, especially in sectors requiring high availability like telecommunications, finance, or government services. The low severity and lack of known exploits reduce the immediate threat level, but organizations should verify that no unsupported OpenBSD 2.4 systems remain active in their network to avoid potential disruptions.

Given that no patches are available for OpenBSD 2.4, the most effective mitigation is to upgrade affected systems to a supported and updated version of OpenBSD where this vulnerability has been addressed. Organizations should conduct thorough asset inventories to identify any legacy systems running OpenBSD 2.4 and plan for their decommissioning or upgrade. Network-level mitigations include implementing strict ingress filtering and firewall rules to block unsolicited or malformed IP packets that could trigger the vulnerability. Additionally, deploying intrusion detection/prevention systems (IDS/IPS) with signatures tuned to detect anomalous IP traffic patterns may help mitigate exploitation attempts. For environments where upgrading is not immediately feasible, isolating vulnerable systems from untrusted networks and restricting access to trusted management networks can reduce exposure. Regular network monitoring and incident response readiness are also recommended to quickly detect and respond to any denial-of-service activity.