CVE-2010-0789 in fuse
Summary
by MITRE
fusermount in FUSE before 2.7.5, and 2.8.x before 2.8.2, allows local users to unmount an arbitrary FUSE filesystem share via a symlink attack on a mountpoint.
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Analysis
by VulDB Data Team • 05/01/2026
The vulnerability identified as CVE-2010-0789 affects the fusermount utility within the Filesystem in Userspace (FUSE) framework, specifically impacting versions prior to 2.7.5 and 2.8.x before 2.8.2. This flaw represents a critical security issue that undermines the integrity of FUSE filesystem operations by enabling local attackers to manipulate mountpoint references through symbolic link attacks. The vulnerability stems from insufficient validation of mountpoint paths, allowing malicious users to exploit the symlink mechanism to unmount filesystems other than the intended target.
The technical implementation of this vulnerability relies on the improper handling of symbolic links within the fusermount utility's path resolution process. When a user attempts to unmount a FUSE filesystem, the utility does not properly validate whether the specified mountpoint is a legitimate directory or if it is a symbolic link pointing elsewhere in the filesystem hierarchy. This weakness creates a race condition where an attacker can create a malicious symlink that points to a different mountpoint, effectively allowing them to unmount arbitrary filesystems. The flaw operates at the operating system level and leverages the fundamental trust model of mountpoint resolution within FUSE implementations.
From an operational perspective, this vulnerability poses significant risks to system security and stability. Local attackers can exploit this weakness to disrupt FUSE-based services, potentially causing data access interruptions or creating unauthorized access paths to sensitive filesystems. The impact extends beyond simple denial of service as attackers could potentially manipulate the filesystem state to gain unauthorized access to resources they should not be able to reach. The vulnerability is particularly concerning in multi-user environments where unprivileged users might exploit it to affect system operations or access other users' mounted filesystems.
The security implications of CVE-2010-0789 align with CWE-367, which addresses the issue of time-of-check to time-of-use (TOCTOU) race conditions in file operations. This vulnerability also maps to ATT&CK technique T1059.007 for executing commands through FUSE utilities and T1490 for creating or modifying system execution environment. The flaw demonstrates poor input validation practices and inadequate privilege separation within the FUSE framework, creating opportunities for privilege escalation and system compromise. Organizations using FUSE-based applications should immediately implement the available patches to address this vulnerability and prevent potential exploitation by malicious actors.
Mitigation strategies for this vulnerability include applying the official patches released by FUSE developers, which typically involve implementing proper symlink resolution checks and path validation mechanisms. System administrators should also consider implementing additional monitoring controls to detect unusual mountpoint operations and establish proper access controls for FUSE filesystems. Regular security audits of FUSE configurations and user permissions can help identify potential exploitation vectors. The patching process should be prioritized in production environments, as the vulnerability allows for arbitrary filesystem unmounting with local user privileges.