CVE-2026-2169 Overview
A command injection vulnerability has been identified in D-Link DWR-M921 firmware version 1.1.50. This vulnerability affects the /boafrm/formLtefotaUpgradeFibocom endpoint, where improper handling of the fota_url argument allows remote attackers to inject and execute arbitrary system commands on the affected device.
Critical Impact
Authenticated remote attackers can execute arbitrary commands on vulnerable D-Link DWR-M921 routers, potentially leading to complete device compromise, network infiltration, and persistent unauthorized access.
Affected Products
- D-Link DWR-M921 firmware version 1.1.50
- D-Link DWR-M921 hardware devices
Discovery Timeline
- 2026-02-08 - CVE-2026-2169 published to NVD
- 2026-02-11 - Last updated in NVD database
Technical Details for CVE-2026-2169
Vulnerability Analysis
This command injection vulnerability (CWE-77) stems from insufficient input validation in the firmware's web management interface. The vulnerable endpoint /boafrm/formLtefotaUpgradeFibocom processes the fota_url parameter without proper sanitization, allowing malicious command sequences to be injected and executed with the privileges of the web server process.
The vulnerability is exploitable remotely over the network and requires low-privilege authentication to access the vulnerable endpoint. Once exploited, an attacker gains the ability to execute arbitrary commands on the underlying operating system, which could lead to complete device takeover.
Root Cause
The root cause is improper neutralization of special elements used in a command (CWE-77) combined with general injection flaws (CWE-74). The fota_url argument passed to the firmware upgrade function is not adequately sanitized before being used in system command execution, allowing shell metacharacters and command sequences to be processed by the underlying shell interpreter.
Attack Vector
The attack vector is network-based, requiring authenticated access to the device's web management interface. An attacker with valid credentials (even low-privilege) can craft a malicious HTTP request to the /boafrm/formLtefotaUpgradeFibocom endpoint with a specially crafted fota_url parameter containing shell commands.
The vulnerability is triggered when the firmware upgrade functionality processes the malicious URL, passing unsanitized input to a system shell command. This allows command chaining using shell metacharacters such as semicolons (;), pipes (|), or command substitution operators ($()).
For detailed technical analysis, refer to the GitHub Issue Discussion and VulDB entry.
Detection Methods for CVE-2026-2169
Indicators of Compromise
- Unusual HTTP POST requests to /boafrm/formLtefotaUpgradeFibocom containing shell metacharacters in the fota_url parameter
- Unexpected outbound network connections from the D-Link router to unknown external hosts
- Unauthorized configuration changes or new user accounts on the device
- Presence of unexpected files or processes running on the router
Detection Strategies
- Monitor web server logs for requests to the vulnerable endpoint with suspicious URL-encoded characters or command injection patterns
- Implement network traffic analysis to detect anomalous POST requests targeting the firmware upgrade functionality
- Deploy intrusion detection rules to identify command injection patterns in HTTP traffic to D-Link devices
- Regularly audit device configurations for unauthorized changes
Monitoring Recommendations
- Enable and centralize logging for all D-Link DWR-M921 devices in your network
- Configure alerts for administrative actions and firmware update attempts outside of scheduled maintenance windows
- Monitor for unusual process spawning or network activity originating from router management interfaces
- Implement network segmentation to isolate IoT and router management interfaces from general network traffic
How to Mitigate CVE-2026-2169
Immediate Actions Required
- Restrict access to the D-Link DWR-M921 web management interface to trusted IP addresses only
- Disable remote management access if not required for operations
- Ensure strong, unique credentials are configured for device administration
- Place affected devices behind a firewall with strict ingress filtering
- Monitor D-Link security advisories for firmware updates addressing this vulnerability
Patch Information
At the time of publication, no official patch information is available from D-Link. Users should monitor the D-Link Security Resources page for firmware updates that address this vulnerability. Additional technical details can be found in the VulDB submission.
Workarounds
- Implement network-level access controls to restrict which hosts can reach the device's management interface
- Disable the web-based management interface if command-line or alternative management methods are available
- Deploy a Web Application Firewall (WAF) or reverse proxy with input validation rules to filter malicious requests
- Consider network isolation for affected devices until a patch is available
# Example iptables rule to restrict management access to trusted IP
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
