CVE-2010-0547 in Samba
Summary
by MITRE
client/mount.cifs.c in mount.cifs in smbfs in Samba 3.4.5 and earlier does not verify that the (1) device name and (2) mountpoint strings are composed of valid characters, which allows local users to cause a denial of service (mtab corruption) via a crafted string.
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Analysis
by VulDB Data Team • 04/30/2026
The vulnerability identified as CVE-2010-0547 resides within the Samba implementation of the mount.cifs utility, specifically in the smbfs component of Samba versions 3.4.5 and earlier. This flaw represents a classic input validation weakness that can be exploited to disrupt system operations through maliciously crafted string inputs. The vulnerability is particularly concerning because it affects the core mounting functionality of CIFS (Common Internet File System) shares, which are widely used for file sharing in enterprise environments. The issue stems from insufficient sanitization of device name and mountpoint strings during the mounting process, creating a pathway for local attackers to manipulate the system's mount table.
The technical implementation of this vulnerability occurs in the client/mount.cifs.c source file where the mount.cifs utility processes user-supplied strings without proper validation of character sets. When a local user provides a crafted string containing invalid or malicious characters, the system fails to validate these inputs before incorporating them into the mtab file, which is the system's mount table that tracks all currently mounted filesystems. This lack of input validation creates a scenario where the mount table becomes corrupted, leading to denial of service conditions that can prevent legitimate mounting operations from succeeding. The vulnerability operates at the system call level where the mount utility interacts with the kernel's filesystem management subsystem, making it particularly impactful for system stability.
The operational impact of this vulnerability extends beyond simple denial of service, as mtab corruption can lead to cascading failures in system administration and file access operations. When the mount table becomes corrupted, subsequent mount operations may fail unpredictably, potentially causing service interruptions for applications that depend on CIFS shares. Local users can exploit this weakness to systematically corrupt the mount table, making it difficult for system administrators to maintain consistent file access policies. The vulnerability is particularly dangerous in enterprise environments where multiple users might be attempting to mount CIFS shares simultaneously, as the corruption can affect the entire system's ability to manage filesystem mounts effectively. This issue directly relates to CWE-170, which addresses improper handling of potentially dangerous input characters, and can be classified under ATT&CK technique T1490 for denial of service through resource consumption and system instability.
Mitigation strategies for CVE-2010-0547 should focus on both immediate patching and defensive system hardening measures. The primary solution involves upgrading to Samba versions 3.4.6 or later, where the input validation has been properly implemented to reject invalid characters in device names and mountpoint strings. System administrators should also implement proper monitoring of the mtab file for unauthorized modifications and establish automated alerts for mount table anomalies. Additional defensive measures include restricting local user privileges for mounting operations, implementing mandatory access controls for the mount utility, and conducting regular security audits of system mount configurations. The vulnerability demonstrates the importance of input validation in system-level utilities and highlights the need for comprehensive security testing of core system components that interface directly with kernel operations. Organizations should also consider implementing network segmentation to limit local user access to critical mounting utilities and establish robust backup procedures for mount table recovery in case of corruption events.