CVE-2025-12942: Netgear R6260 Firmware RCE Vulnerability

CVE-2025-12942 Overview

CVE-2025-12942 is an improper input validation vulnerability [CWE-20] affecting NETGEAR R6260 and R6850 wireless routers. The flaw enables unauthenticated attackers with adjacent network access to execute arbitrary commands on the affected device. Exploitation requires the attacker to occupy a privileged network position, specifically the ability to perform man-in-the-middle (MiTM) attacks and control the DNS server used by the router. The vulnerability affects R6260 firmware through version 1.1.0.86 and R6850 firmware through version 1.1.0.86. NETGEAR disclosed the issue in its November 2025 security advisory.

Critical Impact
A LAN-adjacent attacker who controls DNS resolution and can intercept router traffic can achieve command execution on affected NETGEAR R6260 and R6850 devices, potentially compromising the entire home or small-office network perimeter.

Affected Products

NETGEAR R6260 router (hardware)
NETGEAR R6260 firmware through 1.1.0.86
NETGEAR R6850 router and firmware through 1.1.0.86

Discovery Timeline

2025-11-11 - CVE-2025-12942 published to NVD
2025-11-11 - NETGEAR publishes November 2025 security advisory
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-12942

Vulnerability Analysis

The vulnerability stems from improper input validation [CWE-20] in firmware routines that process data received from external network services. The affected NETGEAR routers accept responses from a DNS server and pass values into downstream handlers without sanitizing them for shell metacharacters or unexpected structure. An attacker controlling the DNS response the router observes can inject content that the router processes as command input rather than data.

Exploitation requires two preconditions. The attacker must be adjacent to the target on the LAN and must control the DNS server the router queries or be positioned to intercept and rewrite DNS traffic through a MiTM technique. These preconditions raise attack complexity, which is reflected in the medium severity rating, but successful exploitation yields high impact to confidentiality, integrity, and availability of the device.

Root Cause

The root cause is the router firmware's failure to validate or sanitize input received from network-facing services before it is used in a security-sensitive operation. When attacker-controlled DNS content reaches an unsafe consumer inside the firmware, it can alter the intended execution flow and result in command execution on the router.

Attack Vector

The attack vector is adjacent network (LAN) rather than remote. An attacker on the same broadcast domain as the router positions themselves as the DNS resolver or as an on-path attacker between the router and its upstream DNS. When the router issues a DNS-related lookup, the attacker returns a crafted response containing malicious payload content. The router parses this response and passes attacker-controlled data into a command context, resulting in execution with router privileges. Full technical exploitation details are not published; see the NETGEAR Security Advisory November 2025 for vendor-supplied information.

Detection Methods for CVE-2025-12942

Indicators of Compromise

Unexpected changes to router configuration, administrative accounts, or DNS settings on R6260 and R6850 devices
Router-originated outbound connections to unknown hosts or unusual ports
LAN clients observing rogue DHCP or DNS servers advertising themselves on the network
Firmware behavior anomalies such as unscheduled reboots or new listening services

Detection Strategies

Monitor for ARP spoofing and rogue DHCP or DNS server activity on trusted LAN segments
Compare DNS responses observed by the router against known-good upstream resolvers to identify tampering
Baseline router firmware version and configuration and alert on unauthorized drift

Monitoring Recommendations

Forward router syslog and administrative event logs to a central collector for correlation
Track outbound flows originating from the router's management interface, which normally should be minimal
Alert on new or unexpected processes and listeners on the router where telemetry is available

How to Mitigate CVE-2025-12942

Immediate Actions Required

Apply the fixed firmware for R6260 and R6850 as published in the NETGEAR Security Advisory November 2025
Restrict LAN access to trusted clients only and segment IoT or guest devices from the router management network
Configure the router to use trusted, hardcoded upstream DNS resolvers where the firmware allows
Rotate router administrative credentials after patching

Patch Information

NETGEAR addressed CVE-2025-12942 in firmware updates released alongside its November 2025 security advisory. Consult the NETGEAR Security Advisory November 2025 and the NETGEAR R6260 Support Page and NETGEAR R6850 Support Page for the fixed firmware versions and installation instructions. Devices running R6260 or R6850 firmware at or below 1.1.0.86 remain exposed.

Workarounds

Enforce Layer 2 protections such as DHCP snooping, dynamic ARP inspection, and port security on managed LAN infrastructure to prevent MiTM positioning
Disable unused router services and remote management features to reduce the attack surface
Replace end-of-support devices with currently supported models if a firmware fix is unavailable for your hardware revision

bash

# Verify router firmware version via the NETGEAR web UI
# Navigate to: ADVANCED > Administration > Router Update
# Confirm the installed version is newer than 1.1.0.86 before returning the device to service