CVE-2006-6053 in Linux
Summary
by MITRE
The ext3fs_dirhash function in Linux kernel 2.6.x allows local users to cause a denial of service (crash) via an ext3 stream with malformed data structures.
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Analysis
by VulDB Data Team • 04/28/2026
The vulnerability identified as CVE-2006-6053 represents a critical flaw in the Linux kernel's ext3 file system implementation that specifically targets the ext3fs_dirhash function. This function is responsible for hashing directory entries within ext3 file systems, which are widely used in Linux environments for their stability and performance characteristics. The vulnerability exists in kernel versions 2.6.x, indicating it affected a broad range of Linux distributions that were prevalent during that era. The flaw manifests when the kernel processes ext3 streams containing malformed data structures, leading to unpredictable behavior that can ultimately result in system crashes.
The technical nature of this vulnerability stems from inadequate input validation within the ext3fs_dirhash function. When processing directory entries, the function fails to properly validate the structure and content of the data it receives from ext3 streams. This lack of proper validation creates an exploitable condition where malformed data structures can cause the kernel to access invalid memory locations or execute unintended code paths. The vulnerability operates at the kernel level, meaning that local users with access to the system can leverage this flaw to trigger a kernel panic or system crash. The flaw does not require special privileges beyond basic user access, making it particularly dangerous as it can be exploited by any local user without elevated permissions.
The operational impact of CVE-2006-6053 extends beyond simple system crashes, as it represents a potential vector for more sophisticated attacks within the context of a compromised system. When a kernel crash occurs due to this vulnerability, it can result in complete system downtime, data loss, and potential corruption of file system structures. The denial of service aspect means that legitimate system operations become disrupted, which can have cascading effects on services running on the affected system. From a security perspective, this vulnerability aligns with CWE-129, which describes improper validation of input boundaries, and can be categorized under the ATT&CK technique T1499.1 for network denial of service. The vulnerability demonstrates how file system level flaws can be leveraged to create system-wide disruptions, making it a significant concern for system administrators and security professionals.
Mitigation strategies for this vulnerability primarily focus on kernel updates and patches that address the input validation issues within the ext3fs_dirhash function. System administrators should immediately apply the relevant kernel patches released by Linux kernel maintainers, which typically include enhanced validation routines for directory entry structures. Additionally, monitoring systems should be implemented to detect unusual patterns in file system operations that might indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper input validation in kernel space code and highlights the need for thorough testing of file system implementations. Organizations should also consider implementing additional security measures such as kernel module whitelisting and restricted user access controls to minimize the potential impact of such vulnerabilities. Regular security audits and vulnerability assessments should include checks for similar issues in other file system implementations and kernel components to ensure comprehensive protection against similar threats.