CVE-1999-0002 in Linux
Summary
by MITRE
Buffer overflow in NFS mountd gives root access to remote attackers, mostly in Linux systems.
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Analysis
by VulDB Data Team • 10/29/2025
The vulnerability identified as CVE-1999-0002 represents a critical buffer overflow flaw within the Network File System mount daemon component that affects numerous Linux distributions and Unix-based systems. This vulnerability specifically targets the mountd service which is responsible for managing NFS mount requests and maintaining the mapping of file systems between networked machines. The flaw exists in how the mountd daemon processes incoming mount requests, particularly when handling overly long arguments or malformed input data that exceeds the allocated buffer space. This buffer overflow condition creates an opportunity for remote attackers to execute arbitrary code with elevated privileges, potentially gaining root access to the affected system.
The technical implementation of this vulnerability stems from improper input validation within the mountd daemon's processing logic. When the daemon receives a mount request containing excessively long argument strings, the fixed-size buffer allocated for processing these inputs becomes overwritten, causing the execution flow to be redirected to attacker-controlled code. This type of vulnerability falls under the Common Weakness Enumeration category of CWE-121, which specifically addresses stack-based buffer overflow conditions where insufficient bounds checking allows memory corruption. The attack vector requires no authentication and can be executed remotely, making it particularly dangerous in networked environments where NFS services are exposed to untrusted networks. The vulnerability's exploitation typically involves crafting a malicious mount request that triggers the buffer overflow, allowing attackers to inject and execute shellcode that escalates privileges to root level access.
The operational impact of CVE-1999-0002 extends far beyond simple privilege escalation, as it fundamentally compromises the security posture of affected systems. Once an attacker gains root access through this vulnerability, they can establish persistent backdoors, modify system files, steal sensitive data, or use the compromised system as a launching point for further attacks within the network. The vulnerability's prevalence in Linux systems during the late 1990s meant that many organizations were exposed to this risk without proper mitigation measures in place. The remote execution capability makes this vulnerability particularly attractive to attackers who can exploit it without requiring physical access to the target system. This type of vulnerability aligns with ATT&CK technique T1068, which describes 'Exploitation for Privilege Escalation' and demonstrates how attackers can leverage system weaknesses to gain elevated access rights.
Mitigation strategies for CVE-1999-0002 involve multiple layers of security controls to address the root cause and prevent exploitation. The most immediate and effective solution is to apply security patches provided by operating system vendors that contain fixed versions of the mountd daemon with proper input validation and buffer management. Organizations should disable unnecessary NFS services and implement strict network segmentation to limit exposure of NFS mountd to untrusted networks. Access control measures including firewall rules that restrict NFS traffic to trusted sources and disabling the mountd service when not required can significantly reduce the attack surface. Additionally, implementing intrusion detection systems that monitor for unusual mount request patterns and conducting regular security audits of NFS configurations helps identify potential exploitation attempts. The vulnerability also underscores the importance of proper software development practices including input validation, bounds checking, and regular security assessments to prevent similar issues in future software releases.