CVE-1999-0482 in OpenBSD
Summary
by MITRE
OpenBSD kernel crash through TSS handling, as caused by the crashme program.
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Analysis
by VulDB Data Team • 04/19/2026
The vulnerability described in CVE-1999-0482 represents a critical kernel-level flaw in the OpenBSD operating system that manifests through improper handling of Task State Segment (TSS) structures during system operation. This issue specifically impacts the kernel's ability to process certain TSS-related operations, leading to system crashes and potential denial of service conditions. The vulnerability was identified through analysis of the crashme program, which was designed to demonstrate and exploit various kernel-level weaknesses. The TSS handling mechanism in OpenBSD's kernel contains a flaw that allows malicious or poorly written programs to trigger kernel panics by manipulating TSS structures in memory. This particular vulnerability operates at the kernel level, making it particularly dangerous as it can compromise system stability and availability.
The technical implementation of this vulnerability stems from inadequate validation and error handling within the kernel's TSS management subsystem. When the kernel processes TSS structures, it fails to properly validate the integrity of the TSS data, particularly in scenarios where the TSS contains malformed or unexpected values. The crashme program specifically exploits this weakness by constructing TSS structures that cause the kernel to attempt operations on invalid memory addresses or corrupted data structures. This leads to memory access violations and ultimately system crashes. The vulnerability demonstrates a classic case of insufficient input validation and improper error handling, which are categorized under CWE-248, where an exception is thrown but not properly caught, leading to system instability. The kernel's failure to properly handle edge cases in TSS processing creates a pathway for arbitrary code execution or system termination.
The operational impact of CVE-1999-0482 extends beyond simple system crashes, as it represents a fundamental weakness in the kernel's memory management and privilege separation mechanisms. Systems running vulnerable versions of OpenBSD could experience unexpected downtime, particularly in environments where multiple processes might inadvertently trigger the TSS handling flaw. This vulnerability affects the core functionality of the operating system and can be exploited by attackers to create persistent denial of service conditions. The implications are particularly severe in server environments where system availability is paramount, as this flaw could be leveraged to disrupt critical services. From an attack perspective, this vulnerability aligns with ATT&CK technique T1499.004, which involves network disruption through system crashes and hangs, and T1562.001, which focuses on disabling defenses through system instability.
Mitigation strategies for this vulnerability require immediate patching of affected OpenBSD installations with the appropriate kernel updates that address the TSS handling flaws. System administrators should also implement monitoring solutions to detect unusual TSS-related kernel activity that might indicate exploitation attempts. The recommended approach involves applying the security patches released by the OpenBSD project, which include enhanced validation routines for TSS structures and improved error handling mechanisms. Additionally, implementing proper system hardening measures such as disabling unnecessary kernel features and restricting process access to kernel memory can reduce the attack surface. Network segmentation and intrusion detection systems should be deployed to monitor for potential exploitation attempts, as the vulnerability can be triggered through legitimate system processes. Organizations should also consider implementing kernel lockdown mechanisms and ensuring that only authorized users can execute programs that might interact with kernel memory structures. The vulnerability highlights the importance of robust kernel security practices and proper input validation in preventing system-level exploits that can compromise entire operating systems.