CVE-1999-0459 in Linux
Summary
by MITRE
Local users can perform a denial of service in Alpha Linux, using MILO to force a reboot.
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Analysis
by VulDB Data Team • 04/18/2026
The vulnerability described in CVE-1999-0459 represents a significant denial of service weakness in Alpha Linux systems that leverages the MILO bootloader to execute unauthorized reboots. This flaw exists at the system level where local users with access to the machine can exploit a design weakness in the bootloader's handling of certain input parameters or commands. The vulnerability specifically targets the Alpha architecture implementation of Linux, which was prevalent in high-performance computing environments and server deployments during the late 1990s era. MILO serves as the primary bootloader for Alpha systems and handles the initial system boot process, making it a critical component that requires robust security controls.
The technical exploitation mechanism involves local users manipulating MILO's command processing or input validation routines to trigger an unexpected system reboot condition. This occurs through specific sequences of commands or parameters that cause MILO to enter an unrecoverable state, forcing the system to restart without proper shutdown procedures. The flaw essentially allows an attacker with local access to execute a privilege escalation attack that results in system unavailability, effectively creating a denial of service condition that can be triggered at will. This represents a fundamental failure in the bootloader's error handling and input validation mechanisms, where malicious or malformed input can cause the system to enter a forced reboot state rather than gracefully handling the error condition.
From an operational impact perspective, this vulnerability severely compromises system availability and reliability in production environments where Alpha Linux systems were deployed. The ability to force reboots at will can result in significant downtime, data loss, and service disruption, particularly in mission-critical applications where system uptime is essential. Network administrators and system operators would face challenges in maintaining service continuity since the vulnerability can be exploited by any user with local access to the system, making it particularly dangerous in multi-user environments where access controls may not be properly enforced. The impact extends beyond simple service interruption to potentially corrupting system state or causing data inconsistencies during forced reboots.
This vulnerability aligns with CWE-248, which describes "Uncaught Exception" in software systems, and represents a classic example of improper exception handling in system-level components. The flaw also maps to ATT&CK technique T1499.004, which covers "Endpoint Denial of Service" through the exploitation of system resources. Organizations should implement strict access controls and user privilege management to prevent unauthorized local access to systems, while also ensuring that bootloader configurations are properly secured. Mitigation strategies include restricting local user access to system boot components, implementing proper input validation in bootloader code, and establishing monitoring systems to detect unauthorized reboot attempts. Additionally, system administrators should consider implementing automated recovery procedures and backup mechanisms to minimize the impact of such denial of service conditions on overall system availability and operational continuity.