CVE-2005-1858 in FUSE
Summary
by MITRE
FUSE 2.x before 2.3.0 does not properly clear previously used memory from unfilled pages when the filesystem returns a short byte count to a read request, which may allow local users to obtain sensitive information.
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Analysis
by VulDB Data Team • 12/28/2024
The vulnerability identified as CVE-2005-1858 affects the FUSE (Filesystem in Userspace) framework version 2.x prior to 2.3.0, presenting a significant information disclosure risk through improper memory handling during read operations. This flaw exists within the core memory management mechanisms of the filesystem implementation where the system fails to adequately clear memory contents from previously used pages when filesystem operations return incomplete data. The issue manifests specifically when a filesystem implementation returns a short byte count to a read request, leaving residual data in memory that could potentially contain sensitive information from previous operations.
The technical root cause of this vulnerability lies in the memory clearing mechanism within FUSE's read request handling process. When a filesystem returns fewer bytes than requested, the system should ensure that any remaining memory space within the allocated buffer is properly cleared to prevent information leakage. However, FUSE 2.x versions before 2.3.0 fail to implement this clearing mechanism correctly, resulting in the persistence of data from previous operations within the memory pages. This behavior creates a condition where local users can potentially access sensitive information that was previously stored in the same memory locations, effectively enabling information disclosure attacks.
From an operational perspective, this vulnerability presents a serious security risk for systems utilizing FUSE-based filesystem implementations. The attack vector requires local system access, making it a privilege escalation or information disclosure vulnerability that could be exploited by malicious users with access to the system. The impact extends beyond simple data exposure, as the leaked information could include cryptographic keys, passwords, personal data, or other sensitive system information that was previously processed by the filesystem. The vulnerability affects any application or service that relies on FUSE for filesystem operations, potentially compromising the confidentiality of data stored or processed through these interfaces.
The security implications of this vulnerability align with CWE-200, which addresses "Information Exposure," and can be mapped to ATT&CK technique T1005 for "Data from Local System." The flaw represents a classic case of memory safety issues where insufficient sanitization of memory buffers leads to information leakage. Organizations using FUSE-based filesystems should prioritize updating to version 2.3.0 or later, as this release includes the necessary memory clearing mechanisms to prevent the exposure of previously used memory contents. Additionally, system administrators should implement monitoring for unusual memory access patterns and consider implementing additional access controls to limit local user privileges where possible. The vulnerability demonstrates the critical importance of proper memory management in kernel-space and userspace filesystem implementations, highlighting that even seemingly minor implementation flaws can result in significant security consequences.