CVE-2005-3858 in Linux
Summary
by MITRE
Memory leak in the ip6_input_finish function in ip6_input.c in Linux kernel 2.6.12 and earlier might allow attackers to cause a denial of service via malformed IPv6 packets with unspecified parameter problems, which prevents the SKB from being freed.
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Analysis
by VulDB Data Team • 06/14/2019
The vulnerability described in CVE-2005-3858 represents a critical memory management flaw within the Linux kernel's IPv6 implementation that specifically affects versions 2.6.12 and earlier. This issue resides in the ip6_input_finish function located in the ip6_input.c source file, where improper handling of malformed IPv6 packets leads to a systematic memory leak that can be exploited to trigger a denial of service condition. The flaw manifests when the kernel encounters IPv6 packets with unspecified parameter problems, creating a scenario where the socket buffer (SKB) structure fails to be properly deallocated from memory.
The technical execution of this vulnerability involves attackers crafting specially malformed IPv6 packets that contain unspecified parameter problems, which causes the kernel's IPv6 input processing pipeline to bypass normal memory cleanup procedures. When the ip6_input_finish function processes these malformed packets, it fails to properly release the associated socket buffer memory resources, resulting in progressive memory consumption over time. This memory leak occurs because the kernel's packet processing logic does not account for all possible error conditions that can arise during IPv6 packet validation, particularly when dealing with unspecified parameter problems that should normally trigger immediate resource cleanup.
The operational impact of this vulnerability extends beyond simple resource exhaustion, as it provides attackers with a straightforward method to consume system memory and potentially cause system instability or complete denial of service. The memory leak accumulates with each malformed packet received, and since the affected kernel versions lack proper memory management safeguards for this specific error condition, the system's available memory becomes progressively depleted. This makes the vulnerability particularly dangerous in networked environments where the kernel is exposed to untrusted network traffic, as attackers can repeatedly send malformed packets to gradually consume all available memory resources.
From a cybersecurity perspective, this vulnerability aligns with CWE-401, which describes improper handling of memory allocation and deallocation, and represents a classic example of a resource leak that can be exploited to create denial of service conditions. The attack vector is relatively simple, requiring only the ability to send IPv6 packets to the target system, making it accessible to a wide range of threat actors. The vulnerability demonstrates a fundamental flaw in kernel security design where error handling paths do not properly maintain resource integrity, creating a persistent memory consumption issue that can be amplified through repeated attacks.
Mitigation strategies for CVE-2005-3858 primarily involve upgrading to kernel versions 2.6.13 or later, where the memory leak has been addressed through improved resource management in the ip6_input_finish function. System administrators should also implement network filtering measures to block malformed IPv6 packets at network boundaries, particularly when dealing with untrusted traffic. Additionally, monitoring for unusual memory consumption patterns and implementing automated alerting systems can help detect exploitation attempts before they cause significant service disruption. The fix implemented in newer kernel versions ensures that socket buffers are properly freed regardless of the specific error conditions encountered during IPv6 packet processing, thereby eliminating the memory leak vulnerability.