CVE-2026-94098: Netcore NBR200V2 Command Injection RCE

CVE-2026-94098 Overview

CVE-2026-94098 is a command injection vulnerability in the Netcore NBR200V2 router running firmware version 1.3.241127.071246. The flaw resides in the /www/cgi-bin/upgrade endpoint, which handles firmware upgrade requests. Attackers can manipulate the QUERY_STRING argument to inject arbitrary operating system commands. The vulnerability is remotely exploitable and public exploit details are available. The vendor was notified but did not respond to the disclosure, leaving affected devices without an official patch.

Critical Impact

Successful exploitation yields arbitrary command execution on the router with the privileges of the CGI process, enabling full device compromise and pivoting into internal networks.

Affected Products

• Netcore NBR200V2 router
• Firmware version 1.3.241127.071246
• Firmware Upgrade CGI Endpoint (/www/cgi-bin/upgrade)

Discovery Timeline

• 2026-09-21 - CVE-2026-94098 published to the National Vulnerability Database (NVD)
• 2026-09-21 - Last updated in NVD database

Technical Details for CVE-2026-94098

Vulnerability Analysis

The vulnerability [CWE-74] affects the firmware upgrade handler exposed through the router's CGI interface. The upgrade binary located at /www/cgi-bin/upgrade reads the HTTP QUERY_STRING environment variable and passes its contents into a shell context without adequate sanitization. Attackers who can reach the router's management interface can append shell metacharacters to the query string. The injected payload executes with the privilege level of the CGI process, which on embedded routers typically runs as root. Because the flaw resides in the firmware upgrade path, exploitation grants persistence over reboots through malicious firmware modification.

Root Cause

The root cause is improper neutralization of special elements passed to a downstream component. The CGI endpoint concatenates user-controlled QUERY_STRING data directly into a shell command invocation. No input validation, allow-listing, or safe execution API is used to isolate the parameter from shell interpretation.

Attack Vector

Exploitation requires network access to the router's HTTP management interface and authenticated privileges, as indicated by the CVSS vector component PR:H. An attacker sends a crafted HTTP request to /cgi-bin/upgrade with shell metacharacters embedded in the query string. The CGI handler expands these metacharacters, causing the injected commands to execute on the device. Public exploit details are referenced through VulDB and a third-party research writeup.

See the VulDB advisory for CVE-2026-94098 and the Netcore NBR200V2 research writeup for additional technical details.

Detection Methods for CVE-2026-94098

Indicators of Compromise

• HTTP requests to /cgi-bin/upgrade containing shell metacharacters such as ;, |, &, backticks, or $() within the query string.
• Unexpected child processes spawned by the upgrade CGI binary, including shells, network utilities, or download tools such as wget or curl.
• Outbound connections from the router to unfamiliar hosts shortly after upgrade endpoint requests.
• New or modified files in writable firmware or configuration partitions following inbound HTTP activity to the management interface.

Detection Strategies

• Inspect web server and access logs on the router for requests to /cgi-bin/upgrade with abnormal query string content or excessive length.
• Deploy network intrusion detection signatures that flag command injection patterns in HTTP query strings destined for the device management interface.
• Baseline management interface traffic and alert on requests from unexpected source addresses, especially from the WAN side.

Monitoring Recommendations

• Forward router syslog output to a centralized logging platform for correlation with endpoint and network telemetry.
• Monitor DNS and firewall logs for lookups or connections initiated by the router to unknown external hosts.
• Track configuration and firmware version changes to identify unauthorized modifications resulting from exploitation.

How to Mitigate CVE-2026-94098

Immediate Actions Required

• Restrict access to the router's HTTP management interface to trusted internal management networks only, and block WAN-side access.
• Change all administrative credentials on the device, since exploitation requires authenticated access per the CVSS vector.
• Isolate affected NBR200V2 devices on a dedicated network segment until an official firmware update is available.
• Consider replacing the device if it operates in a sensitive environment, as the vendor has not responded to the disclosure.

Patch Information

No vendor patch is available at the time of publication. The VulDB record notes that Netcore was contacted early about this disclosure but did not respond. Monitor the VulDB entry for CVE-2026-94098 and Netcore vendor channels for future firmware releases.

Workarounds

• Disable remote administration on the WAN interface through the router's configuration panel.
• Place the router behind an upstream firewall that filters inbound HTTP and HTTPS requests to the management interface.
• Enforce access control lists that permit management traffic only from administrator workstations.
• Rotate administrative credentials to strong, unique values and audit account usage regularly.

# Example iptables rule to restrict management interface access
iptables -A INPUT -p tcp --dport 80 -s 192.0.2.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.0.2.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP