CVE-2005-3660 in Linux
Summary
by MITRE
Linux kernel 2.4 and 2.6 allows attackers to cause a denial of service (memory exhaustion and panic) by creating a large number of connected file descriptors or socketpairs and setting a large data transfer buffer, then preventing Linux from being able to finish the transfer by causing the process to become a zombie, or closing the file descriptor without closing an associated reference.
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Analysis
by VulDB Data Team • 08/25/2025
This vulnerability exists in the linux kernel versions 2.4 and 2.6 and represents a significant denial of service flaw that can lead to system panic and memory exhaustion. The vulnerability stems from improper handling of file descriptors and socket pairs within the kernel's networking subsystem, specifically when dealing with large data transfer buffers. Attackers can exploit this weakness by creating numerous connected file descriptors or socket pairs and configuring substantial data transfer buffers, which consumes significant system resources. The flaw is particularly dangerous because it can be triggered through seemingly legitimate network operations that create multiple connection endpoints.
The technical implementation of this vulnerability involves a race condition and resource management issue within the kernel's socket handling mechanisms. When processes create socket pairs and set large buffers for data transfer, the kernel allocates memory to accommodate these operations. However, the vulnerability occurs when the process becomes a zombie state or when file descriptors are closed without properly releasing associated reference counts. This creates a situation where kernel memory structures remain allocated and unreleased, leading to gradual memory exhaustion. The issue is classified under cwe-400 which deals with unchecked resource allocation, and it aligns with attack techniques described in the attack pattern taxonomy where adversaries exploit resource exhaustion to cause system instability.
The operational impact of this vulnerability is severe as it can render affected systems completely unusable through memory exhaustion attacks. System administrators may observe increasing memory consumption until the kernel panics and reboots the system. The vulnerability affects any linux system running kernel versions 2.4 or 2.6, making it particularly concerning for older server deployments and embedded systems that may not have received timely updates. The attack can be executed with relatively simple tools and does not require elevated privileges, making it accessible to a wide range of threat actors. Network services running on affected systems become vulnerable to this attack, potentially causing widespread disruption to network availability.
Mitigation strategies for this vulnerability include applying the appropriate kernel patches released by the linux kernel community, which address the resource management issues in socket handling and file descriptor cleanup. System administrators should also implement connection limits and resource monitoring to detect unusual memory consumption patterns that might indicate exploitation attempts. Network administrators can deploy rate limiting and connection tracking mechanisms to prevent the rapid creation of multiple file descriptors. The fix typically involves ensuring proper reference counting and cleanup of socket resources even when processes become zombies or when file descriptors are closed prematurely. Additionally, implementing memory limits and resource controls through kernel parameters can help prevent complete system exhaustion while the permanent patches are being deployed across the infrastructure.