CVE-2021-38526 in RAX35
Summary
by MITRE • 08/11/2021
Certain NETGEAR devices are affected by a buffer overflow by an unauthenticated attacker. This affects RAX35 before 1.0.3.94, RAX38 before 1.0.3.94, and RAX40 before 1.0.3.94.
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Analysis
by VulDB Data Team • 08/16/2021
The vulnerability identified as CVE-2021-38526 represents a critical buffer overflow flaw affecting specific NETGEAR RAX series routers including models RAX35, RAX38, and RAX40. This issue stems from inadequate input validation within the device's firmware, creating a potential entry point for unauthenticated attackers to exploit the network infrastructure. The affected firmware versions prior to 1.0.3.94 demonstrate a fundamental security weakness that could enable remote code execution and complete system compromise without requiring any authentication credentials. The vulnerability resides in the device's handling of network requests and data processing functions, where insufficient bounds checking allows malicious inputs to overwrite adjacent memory locations.
This buffer overflow vulnerability operates at the application layer and presents significant operational risks to network security infrastructure. The flaw allows an attacker to craft malicious network packets or HTTP requests that, when processed by the vulnerable router firmware, trigger memory corruption. The technical implementation involves the device's web interface or network protocol handlers failing to properly validate the length of incoming data before copying it into fixed-size buffers. This creates a classic stack-based buffer overflow scenario where attacker-controlled data can overwrite return addresses, function pointers, or other critical memory structures. According to CWE classification, this vulnerability maps to CWE-121 Stack-based Buffer Overflow, which is a well-documented weakness in software development practices. The ATT&CK framework categorizes this as a privilege escalation technique through software exploitation, specifically targeting network infrastructure devices to gain persistent access to corporate or residential networks.
The operational impact of this vulnerability extends beyond simple device compromise, as it enables attackers to establish persistent backdoors within network perimeters. Once exploited, the attacker gains the ability to modify network configurations, intercept traffic, redirect connections, or even use the compromised device as a pivot point for attacking internal network resources. The unauthenticated nature of the attack means that any individual with network access can exploit this vulnerability, making it particularly dangerous in environments where physical access to network devices is not strictly controlled. The affected RAX series devices are commonly deployed in residential and small office environments, where network security measures may be less robust than in enterprise settings, amplifying the potential impact. Organizations using these devices face significant risk of data breaches, network disruption, and potential lateral movement within their network infrastructure.
Mitigation strategies for CVE-2021-38526 must prioritize immediate firmware updates from NETGEAR to versions 1.0.3.94 or later, which contain the necessary patches to address the buffer overflow conditions. Network administrators should implement network segmentation and access controls to limit potential attack surfaces, while also monitoring for suspicious network activity that might indicate exploitation attempts. The implementation of intrusion detection systems can help identify anomalous traffic patterns associated with exploitation attempts, and regular vulnerability assessments should be conducted to ensure all network devices remain patched against similar vulnerabilities. Additional defensive measures include disabling unnecessary services and ports on affected devices, implementing strong network access controls, and establishing incident response procedures specifically tailored to address router compromise scenarios. The vulnerability highlights the importance of regular firmware updates and proper input validation in embedded systems, as these devices often serve as critical points of entry for network attackers seeking to establish persistent access to larger network environments.