CVE-2021-38523 in R6400
Summary
by MITRE • 08/11/2021
NETGEAR R6400 devices before 1.0.1.70 are affected by a stack-based buffer overflow by an authenticated user.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/16/2021
The vulnerability identified as CVE-2021-38523 affects NETGEAR R6400 routers running firmware versions prior to 1.0.1.70, representing a critical stack-based buffer overflow flaw that can be exploited by authenticated users. This vulnerability resides within the device's web interface handling mechanisms, specifically in how the router processes user input through HTTP request parameters. The flaw manifests when an authenticated attacker submits maliciously crafted input to the router's administration interface, potentially leading to arbitrary code execution on the affected device.
The technical implementation of this buffer overflow occurs in the router's web server component where user-supplied data is copied into insufficiently sized stack buffers without proper bounds checking. This allows an attacker who has already gained administrative credentials to manipulate the program flow by overwriting adjacent stack memory locations. The vulnerability is classified as a stack-based buffer overflow under CWE-121, which represents a fundamental memory safety issue where data written to a buffer extends beyond its allocated memory boundaries. The affected parameter handling typically occurs in forms or API endpoints that process configuration data, system settings, or network parameters through the web interface.
Operationally, this vulnerability presents significant risks to network security as it allows authenticated attackers to execute arbitrary code on the router with the privileges of the web server process. The impact extends beyond simple privilege escalation since routers serve as core network infrastructure components that control traffic flow, manage network access, and often provide administrative interfaces for entire network segments. Successful exploitation could enable attackers to modify routing tables, redirect traffic to malicious servers, disable security features, or establish persistent backdoors within the network. The authenticated requirement reduces the attack surface compared to unauthenticated vulnerabilities but remains highly dangerous given that router administrators often have elevated privileges and may be targeted through credential theft or social engineering attacks.
The mitigation strategy for this vulnerability requires immediate firmware updates from NETGEAR to version 1.0.1.70 or later, which contain patches addressing the buffer overflow conditions. Network administrators should also implement additional security controls such as restricting administrative access to trusted networks, implementing strong authentication mechanisms including multi-factor authentication, and monitoring for suspicious activities in router administration logs. The vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1021.001 for remote services, as exploitation would likely involve executing commands through the affected web interface. Organizations should also consider network segmentation and implementing network access controls to limit the potential impact if an attacker compromises a router, as the compromised device could serve as a pivot point for further network exploration and lateral movement attacks.