CVE-2026-11739: NETGEAR Nighthawk RCE Vulnerability

CVE-2026-11739 Overview

CVE-2026-11739 is a command injection vulnerability [CWE-78] affecting certain NETGEAR Nighthawk devices. A network-adjacent attacker capable of intercepting and modifying local network traffic (attacker-in-the-middle) can compromise the confidentiality and integrity of the affected device. Exploitation requires the attacker to sit on the same broadcast domain or achieve a position to manipulate LAN traffic between the device and an upstream endpoint. NETGEAR published fixes as part of its August 2026 Security Advisory covering a broad set of routers, mesh systems, and switches in the Nighthawk product line.

Critical Impact
Successful exploitation allows an attacker-in-the-middle on the local network to inject operating system commands, leading to loss of device confidentiality and integrity.

Affected Products

NETGEAR Nighthawk routers including RAX20, RAX35, RAX35v2, RAX41, RAX41v2, RAX42, RAX42v2, RAX43, RAX43v2, RAX45, RAX49s, RAX50, RAX50v2, RAX80, RAX200, RAXE500, RS700, XR1000, and XR1000v2
NETGEAR mesh Wi-Fi systems MR60, MR70, MR90
NETGEAR mesh satellites MS60, MS70, MS90

Discovery Timeline

2026-08-11 - CVE-2026-11739 published to NVD alongside the NETGEAR August 2026 Security Advisory
2026-08-12 - Last updated in NVD database

Technical Details for CVE-2026-11739

Vulnerability Analysis

The flaw is classified as an OS command injection weakness [CWE-78]. Affected NETGEAR Nighthawk devices construct shell commands using data derived from network traffic without adequate sanitization. Because the attack vector is Adjacent (AV:A) and requires the attacker to intercept and modify traffic, the exploit surface centers on unauthenticated communication paths reachable on the local network segment.

An attacker positioned between the device and a trusted upstream service can substitute or alter response fields consumed by the router. When the injected payload reaches the vulnerable parser, shell metacharacters break out of the intended argument context and execute arbitrary commands on the underlying Linux firmware.

Root Cause

The root cause is improper neutralization of special elements used in OS commands. Input sourced from network responses is passed to a shell interpreter without escaping, quoting, or allow-list validation. This is a common pattern in embedded router firmware where helper utilities are invoked through system() or popen() calls built via string concatenation.

Attack Vector

Exploitation requires attacker-in-the-middle (AITM) positioning on the local network. The attacker must first intercept traffic between the Nighthawk device and a service it queries, then modify the response to embed command injection payloads. Because user interaction is not required and no authentication is needed, any adversary with LAN-adjacent access — such as a rogue Wi-Fi client, a compromised IoT device, or a malicious switch — can attempt the attack.

No public proof-of-concept exploit is available at the time of publication, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. The EPSS score is approximately 1.05% (61st percentile) as of 2026-08-13.

Detection Methods for CVE-2026-11739

Indicators of Compromise

Unexpected outbound connections originating from the Nighthawk device to attacker-controlled infrastructure
Presence of new processes or persistence artifacts on the router (where accessible via vendor diagnostics)
ARP table anomalies or duplicate MAC addresses indicating ARP spoofing on the local segment
Modified DNS responses or unexpected TLS certificate errors on traffic transiting the affected device

Detection Strategies

Monitor DHCP and ARP tables for unauthorized devices that could establish an attacker-in-the-middle position
Inspect firewall telemetry for anomalous egress from router management interfaces
Correlate wireless client join events with subsequent LAN-side scanning or spoofing activity
Compare firmware version strings reported by the router against the fixed versions listed in the NETGEAR advisory

Monitoring Recommendations

Enable network flow logging (NetFlow, IPFIX, or sFlow) on upstream switches to identify unusual traffic patterns
Deploy network detection sensors to flag ARP spoofing, rogue DHCP, and unexpected LLMNR/NBNS activity
Alert on management-plane authentication attempts against the router from unfamiliar hosts

How to Mitigate CVE-2026-11739

Immediate Actions Required

Apply the firmware updates published in the NETGEAR August 2026 Security Advisory for every affected Nighthawk model in the environment
Enumerate deployed NETGEAR devices and confirm each is running a firmware version at or above the fixed release
Restrict physical and wireless access to network segments hosting affected devices until patched

Patch Information

NETGEAR has released firmware updates addressing CVE-2026-11739 for the affected Nighthawk routers, mesh systems, and satellites. Refer to each product's support page (for example, NETGEAR RAX50 Product Support or NETGEAR RAXE500 Product Support) to download the model-specific firmware and follow the vendor upgrade procedure through the router web UI or NETGEAR Nighthawk mobile app.

Workarounds

Segment untrusted clients (guest Wi-Fi, IoT devices) onto isolated VLANs that cannot reach the router management plane
Enforce WPA3 or WPA2-Enterprise authentication and disable open or WEP/WPA legacy SSIDs to reduce LAN-adjacent exposure
Disable unused services and remote management on the affected devices until firmware is applied
Deploy static ARP entries or dynamic ARP inspection (DAI) on managed switches to hinder attacker-in-the-middle positioning

bash

# Example: enable Dynamic ARP Inspection on a managed switch VLAN
# (Cisco IOS syntax - adapt to your switch vendor)
configure terminal
ip arp inspection vlan 10
interface range GigabitEthernet0/1 - 24
  ip arp inspection trust
end
write memory