CVE-2018-21093

Vulnerability

A stack-based buffer overflow vulnerability exists in the firmware of numerous NETGEAR routers, modem routers, wireless extenders, and Orbi satellites. The issue affects the following models running firmware prior to the specified versions: D8500 before 1.0.3.42, EX3700 before 1.0.0.70, EX3800 before 1.0.0.70, EX6000 before 1.0.0.30, EX6100 before 1.0.2.24, EX6120 before 1.0.0.40, EX6130 before 1.0.0.22, EX6150 before 1.0.0.42, EX6200 before 1.0.3.88, EX7000 before 1.0.0.66, R6250 before 1.0.4.26, R6300-2CXNAS before 1.0.3.60, R6300v2 before 1.0.4.28, R6400 before 1.0.1.36, R6400v2 before 1.0.2.52, R6700 before 1.0.1.46, R6900 before 1.0.1.46, R7000 before 1.0.9.28, R7000P before 1.3.1.44, R6900P before 1.3.1.44, R7100LG before 1.0.0.46, R7300 before 1.0.0.68, R7900 before 1.0.2.10, R8000 before 1.0.4.18, R8000P before 1.3.0.10, R7900P before 1.3.0.10, R8500 before 1.0.2.122, R8300 before 1.0.2.122, RBW30 before 2.1.2.6, WN2500RPv2 before 1.0.0.54, and WNR3500Lv2 before 1.2.0.56 [1]. The vulnerability can be triggered without authentication.

Exploitation

An unauthenticated attacker with network access to the affected device can exploit this stack-based buffer overflow by sending specially crafted packets or requests to the device's listening services. The attack does not require any prior credentials or user interaction, making it remotely exploitable over the network [1].

Impact

Successful exploitation of this vulnerability could allow the attacker to cause a denial of service through device crash or potentially achieve arbitrary code execution on the device with elevated privileges (likely root). The exact impact may vary depending on the device and firmware version, but the advisory notes it is a pre-authentication vulnerability, enabling remote compromise without any access control bypass [1].

Mitigation

NETGEAR has released fixed firmware versions for all affected models. Users should upgrade their devices to the patched firmware versions listed above (e.g., D8500 to 1.0.3.42 or later, EX3700 to 1.0.0.70 or later, etc.). The latest firmware can be downloaded from the NETGEAR Support website by searching for the specific model number [1]. No workaround or mitigation other than installing the fixed firmware is mentioned in the reference.