CVE-2003-0551 in Linux
Summary
by MITRE
The STP protocol implementation in Linux 2.4.x does not properly verify certain lengths, which could allow attackers to cause a denial of service.
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Analysis
by VulDB Data Team • 06/29/2021
The vulnerability identified as CVE-2003-0551 represents a critical flaw in the Spanning Tree Protocol implementation within Linux kernel versions 2.4.x series. This issue resides in the network protocol handling layer where the kernel's STP implementation fails to properly validate packet length parameters during network topology management operations. The vulnerability specifically targets the bridge management functionality that relies on STP to prevent network loops in switched environments, making it particularly dangerous in enterprise networking scenarios where network stability is paramount.
The technical flaw manifests when the kernel receives STP packets containing malformed length fields that exceed expected boundaries or fall below minimum required values. The insufficient input validation allows attackers to craft specially crafted network packets that trigger buffer overflow conditions or memory corruption within the kernel's network bridge subsystem. This improper verification occurs during the processing of bridge configuration messages, where the kernel does not adequately check whether the received packet lengths match expected protocol specifications before proceeding with packet parsing and processing operations. The vulnerability operates at the network protocol level and can be exploited through remote network access without requiring authentication or privileged access.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially compromise entire network infrastructure stability. When exploited, the vulnerability can cause the affected Linux system to become unresponsive or crash entirely, leading to network outages that can affect multiple connected devices and services. In switched network environments where STP is actively used to maintain network topology consistency, an attacker could repeatedly trigger the vulnerability to maintain persistent denial of service conditions. The attack vector is particularly concerning because it can be executed remotely over the network without requiring physical access or user interaction, making it a significant threat to network availability and business continuity.
Mitigation strategies for CVE-2003-0551 should prioritize immediate kernel updates to versions that contain proper input validation for STP packet lengths. Network administrators should implement network segmentation and access control measures to limit exposure of affected systems to untrusted networks. The vulnerability aligns with CWE-129 Input Validation and CWE-770 Allocation of Resources Without Limits or Throttling categories, reflecting the fundamental flaw in resource handling and input sanitization. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 Network Denial of Service and T1595.001 Network Topology Discovery, as it enables both service disruption and network infrastructure reconnaissance. Organizations should also deploy network monitoring solutions to detect anomalous STP packet patterns and implement proper network access controls to prevent unauthorized access to network infrastructure devices running vulnerable kernel versions.