CVE-2018-21135

Vulnerability

A stack-based buffer overflow vulnerability exists in the firmware of certain NETGEAR router models [1]. The flaw is triggered by an authenticated user, meaning the attacker must already have valid credentials to access the device's administrative interface. Affected models and fixed versions include: R6700 before 1.0.1.48, R7500 before 1.0.0.124, R7800 before 1.0.2.58, R8900 before 1.0.4.2, R9000 before 1.0.4.2, WNDR3700v4 before 1.0.2.102, WNDR4300v1 before 1.0.2.104, WNDR4300v2 before 1.0.0.56, WNDR4500v3 before 1.0.0.56, and WNR2000v5 before 1.0.0.68 [1].

Exploitation

To exploit this vulnerability, an attacker must first authenticate to the router's administrative web interface with valid credentials [1]. Once authenticated, the attacker can send a specially crafted request that causes a stack-based buffer overflow, potentially leading to arbitrary code execution [1]. No details on the exact request or data required are provided in the reference.

Impact

Successful exploitation allows an authenticated attacker to execute arbitrary code on the affected router, potentially gaining full control of the device [1]. This could lead to disclosure of sensitive information, modification of device configuration, or denial of service. The impact is limited to authenticated users, which reduces the attack surface but remains significant if credentials are compromised or default credentials are still in use.

Mitigation

The vulnerability is fixed by upgrading to the latest firmware version for each affected model, as listed in the vulnerability section [1]. NETGEAR released these firmware updates prior to the publication of this CVE; the exact release dates are not specified in the reference. Users are strongly recommended to download the appropriate firmware from NETGEAR Support and install it according to the product's user manual or release notes [1]. No workarounds or mitigations other than patching are disclosed.