CVE-1999-0485 in OpenBSD
Summary
by MITRE
Remote attackers can cause a system crash through ipintr() in ipq in OpenBSD.
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Analysis
by VulDB Data Team • 04/18/2026
The vulnerability identified as CVE-1999-0485 represents a critical denial of service flaw within the OpenBSD operating system's network stack implementation. This vulnerability specifically targets the ipq module which handles packet queuing operations within the internet protocol layer. The flaw manifests in the ipintr() function which processes incoming network packets and manages their queuing within the kernel's packet queue structures. When exploited, this vulnerability allows remote attackers to trigger a system crash by sending specially crafted network packets that cause the kernel to enter an unstable state during packet processing operations.
The technical root cause of this vulnerability lies in inadequate input validation and memory management within the packet queue handling code. The ipintr() function fails to properly validate packet headers and queue states when processing incoming packets, leading to potential buffer overflows or invalid memory access conditions. This flaw operates at the kernel level within the network packet processing pipeline, making it particularly dangerous as it can be exploited without requiring any authentication or local access to the target system. The vulnerability demonstrates characteristics consistent with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read errors that can occur during memory operations.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable more sophisticated attack vectors within the broader context of network-based exploitation. Attackers can leverage this vulnerability to perform distributed denial of service attacks against OpenBSD systems by sending malformed packets to target hosts, causing widespread service disruption. The vulnerability affects systems running various versions of OpenBSD where the ipq module is active, particularly those configured to handle network traffic. From an adversarial perspective, this flaw aligns with ATT&CK technique T1499.004 which involves network denial of service attacks targeting system availability. The remote exploitability means that attackers can target systems from anywhere on the network without requiring physical access or prior authentication credentials.
Mitigation strategies for this vulnerability require immediate system updates and patches from OpenBSD maintainers to address the underlying kernel code issues. System administrators should implement network segmentation and access controls to limit exposure to potentially malicious traffic while waiting for official patches. Network intrusion detection systems can be configured to monitor for anomalous packet patterns that might indicate exploitation attempts. Additionally, implementing proper firewall rules to filter malformed packets and limiting unnecessary network services can reduce the attack surface. The vulnerability highlights the importance of kernel security reviews and proper input validation in operating system components, particularly those handling network traffic. Organizations should also consider implementing redundant systems and failover mechanisms to maintain service availability during potential exploitation events. Regular security audits and vulnerability assessments should be conducted to identify similar issues in other kernel components and ensure overall system resilience against similar attacks.