CVE-1999-0798 in FreeBSD
Summary
by MITRE
Buffer overflow in bootpd on OpenBSD, FreeBSD, and Linux systems via a malformed header type.
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Analysis
by VulDB Data Team • 04/17/2026
The vulnerability identified as CVE-1999-0798 represents a critical buffer overflow condition affecting bootpd services across multiple operating systems including OpenBSD, FreeBSD, and Linux distributions. This issue resides within the bootstrap protocol daemon which handles network boot requests from client machines during the initial system startup phase. The flaw specifically manifests when the bootpd service processes incoming packets containing malformed header types that exceed the allocated buffer space, creating an exploitable condition that can be leveraged by remote attackers to execute arbitrary code on affected systems.
The technical implementation of this buffer overflow stems from inadequate input validation within the bootpd daemon's packet parsing routine. When processing network boot requests, the service fails to properly bounds-check the header type field in incoming packets, allowing maliciously crafted data to overwrite adjacent memory locations. This memory corruption can be exploited to overwrite return addresses, function pointers, or other critical control data structures within the process memory space. The vulnerability operates at the network layer where bootpd typically listens on UDP port 67 and 68 for DHCP and BOOTP requests, making it accessible to any remote attacker capable of sending malformed packets to the target system.
The operational impact of this vulnerability extends beyond simple denial of service conditions to encompass full system compromise capabilities. An attacker exploiting this buffer overflow can potentially execute arbitrary code with the privileges of the bootpd process, which typically runs with elevated system permissions. This compromise can lead to complete system takeover, data exfiltration, or establishment of persistent backdoors within the network infrastructure. The affected systems are particularly vulnerable during network boot operations when the bootpd service is actively processing client requests, making this a significant threat to network security and infrastructure integrity.
Mitigation strategies for this vulnerability require immediate implementation of system updates and patches provided by the respective operating system vendors. System administrators should ensure that all affected systems receive the latest security patches addressing the buffer overflow condition in bootpd implementations. Network segmentation and firewall rules can provide temporary protection by restricting access to UDP ports 67 and 68 from untrusted networks. Additionally, implementing network monitoring solutions to detect malformed bootp packets can aid in early threat identification. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation that violates fundamental security principles. From an attack framework perspective, this vulnerability would map to techniques involving remote code execution and privilege escalation within the ATT&CK methodology, specifically targeting the execution and privilege escalation phases of the attack lifecycle.