CVE-2003-0252 in nfs-utils
Summary
by MITRE
Off-by-one error in the xlog function of mountd in the Linux NFS utils package (nfs-utils) before 1.0.4 allows remote attackers to cause a denial of service and possibly execute arbitrary code via certain RPC requests to mountd that do not contain newlines.
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Analysis
by VulDB Data Team • 08/21/2025
The vulnerability identified as CVE-2003-0252 represents a critical off-by-one error within the xlog function of the mountd daemon in the Linux NFS utils package. This flaw exists in versions prior to 1.0.4 and demonstrates a classic buffer manipulation issue that can be exploited remotely to compromise system integrity. The vulnerability specifically affects the Network File System (NFS) implementation where mountd serves as a crucial component for managing NFS mount requests and maintaining logs of these operations.
The technical nature of this vulnerability stems from improper input validation within the xlog function, which processes RPC requests sent to the mountd service. When remote attackers submit specially crafted RPC requests that lack newline characters, the function fails to properly handle the boundary conditions, leading to an off-by-one error in memory allocation or string handling. This type of error falls under the CWE-121 category of Buffer Overflow, specifically involving stack-based buffer overflows that can be triggered by improper boundary checks in input processing functions. The vulnerability creates a condition where the application writes one byte beyond the allocated buffer space, potentially corrupting adjacent memory locations.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling remote code execution. Attackers can leverage this flaw to disrupt NFS services by causing the mountd daemon to crash or behave unpredictably, resulting in service interruption for legitimate users. More critically, the off-by-one error creates memory corruption that could be exploited to inject and execute arbitrary code on the affected system. This represents a significant threat to networked environments where NFS services are actively used, as it allows unauthorized parties to gain control of the system and potentially escalate privileges to root access. The vulnerability particularly affects systems running older versions of nfs-utils where the input validation mechanisms were insufficient to prevent malformed RPC requests from causing memory corruption.
Mitigation strategies for this vulnerability require immediate patching of the nfs-utils package to version 1.0.4 or later, which contains the necessary fixes for the buffer handling issues in the xlog function. System administrators should also implement network segmentation and access controls to limit exposure of NFS services to untrusted networks, as recommended by the ATT&CK framework's network service scanning and exploitation techniques. Additional protective measures include monitoring for unusual RPC traffic patterns and implementing intrusion detection systems that can identify malformed NFS requests. The vulnerability highlights the importance of proper input validation and boundary checking in network services, aligning with security best practices that emphasize defense in depth and regular security updates to address known vulnerabilities in system components. Organizations should also conduct comprehensive vulnerability assessments to identify other potentially affected systems running older versions of the nfs-utils package.