CVE-2026-41924: WDR201A WiFi Extender RCE Vulnerability

CVE-2026-41924 Overview

CVE-2026-41924 is an operating system (OS) command injection vulnerability [CWE-78] in the WDR201A WiFi Extender (Hardware V2.1, Firmware LFMZX28040922V1.02). The flaw resides in the makeRequest.cgi binary and affects the set_time and StartSniffer functions. Unauthenticated remote attackers can submit a crafted POST request with ampersand-delimited parameters that bypass input sanitization. Successful exploitation yields arbitrary shell command execution on the device, with payloads up to 31 bytes processed through the date command or the channel parameter.

Critical Impact
Unauthenticated remote attackers can execute arbitrary shell commands on affected WDR201A WiFi Extenders, leading to full device compromise.

Affected Products

WDR201A WiFi Extender, Hardware revision V2.1
WDR201A WiFi Extender, Firmware LFMZX28040922V1.02
The vulnerable component is the makeRequest.cgi binary served by the device web interface

Discovery Timeline

2026-05-04 - CVE-2026-41924 published to the National Vulnerability Database (NVD)
2026-05-05 - Last updated in the NVD database

Technical Details for CVE-2026-41924

Vulnerability Analysis

The WDR201A exposes a CGI endpoint at makeRequest.cgi that dispatches requests to internal handler functions based on parameters supplied in the POST body. Two of these handlers, set_time and StartSniffer, pass attacker-controlled values into shell command strings without adequate sanitization. The set_time handler invokes the system date utility using user-supplied time values, while StartSniffer consumes a channel parameter that is concatenated into a sniffer command line. Because the parser splits parameters on the ampersand character, attackers can append additional fields that survive sanitization checks and reach the shell. The injected commands run with the privileges of the embedded web server, which on consumer-grade extenders typically equates to root. The 31-byte limit on injected commands constrains payload size but is sufficient to fetch and execute a second-stage script using utilities such as wget or tftp.

Root Cause

The root cause is improper neutralization of special elements used in an OS command [CWE-78]. Input validation in makeRequest.cgi operates on a single expected parameter at a time and does not account for ampersand-delimited additional fields. Values reach system()-style invocations without shell metacharacter escaping or argument-vector execution.

Attack Vector

Exploitation requires only network reachability to the device administrative interface. No authentication or user interaction is required. An attacker submits a POST request to makeRequest.cgi targeting either the set_time or StartSniffer handler and embeds shell metacharacters such as backticks, semicolons, or command substitution within the trailing ampersand-delimited fields. The injected command is executed by the underlying shell when the handler invokes date or processes the channel value.

A verified proof-of-concept exploit was not available in the source data. Refer to the VulnCheck Security Advisory and the GitHub IoT Vulnerability Disclosure for detailed technical write-ups.

Detection Methods for CVE-2026-41924

Indicators of Compromise

HTTP POST requests to /makeRequest.cgi containing shell metacharacters such as backticks, ;, |, $(), or multiple &-delimited parameter pairs.
Outbound connections from WDR201A devices to unfamiliar hosts, particularly to TFTP, HTTP, or IRC services that may serve second-stage payloads.
Unexpected processes such as wget, tftp, nc, or shell instances spawned as children of the device web server.

Detection Strategies

Inspect web server and reverse-proxy logs for POST bodies to makeRequest.cgi that include the strings set_time or StartSniffer alongside shell metacharacters.
Deploy network intrusion detection signatures that match ampersand-delimited parameter chaining within requests to consumer router CGI endpoints.
Correlate authentication-free administrative requests with anomalous outbound traffic from the same device IP address.

Monitoring Recommendations

Segment IoT and consumer networking equipment onto isolated VLANs and monitor north-south flows for command-and-control patterns.
Capture full PCAPs at the WAN/LAN boundary for any management traffic destined to extender administrative ports.
Alert on firmware version LFMZX28040922V1.02 appearing in asset inventories and treat the host as exposed until remediated.

How to Mitigate CVE-2026-41924

Immediate Actions Required

Restrict access to the WDR201A administrative interface to trusted management hosts using upstream firewall or ACL rules.
Disable remote management features if not strictly required and ensure the device is not reachable from the internet.
Audit network logs for prior POST requests to makeRequest.cgi containing shell metacharacters and treat matches as suspected compromise.

Patch Information

No vendor patch was identified in the available references at publication time. Track the VulnCheck Security Advisory for any firmware updates released after disclosure. Until a fixed firmware image is published, organizations should treat the device as a permanently vulnerable asset and apply compensating controls.

Workarounds

Place the WDR201A behind a firewall that blocks inbound HTTP requests to its administrative interface from untrusted networks.
Replace the affected device with a maintained alternative if a fixed firmware image is not made available.
Where the device must remain in service, enforce strict egress filtering so that any successful injection cannot retrieve secondary payloads.

bash

# Example upstream firewall rule restricting access to the extender admin interface
# Replace 192.0.2.10 with the extender IP and 198.51.100.0/24 with the trusted management subnet
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 80 -s 198.51.100.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 80 -j DROP
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 443 -s 198.51.100.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d 192.0.2.10 --dport 443 -j DROP