CVE-2026-102240 Overview
CVE-2026-102240 is an operating system command injection vulnerability in the Netcore NAP930 router, firmware version 0.1.241010.141410. The flaw resides in the eval function of the /www/cgi-bin/network_tools script within the Network Tools CGI component. Attackers can manipulate the sid argument to inject arbitrary shell commands. The vulnerability is remotely exploitable and public exploit details have been disclosed. The vendor was contacted before public disclosure but did not respond.
Critical Impact
Unauthenticated remote attackers can execute arbitrary operating system commands on the router, leading to full device compromise, traffic interception, and potential pivoting into internal networks.
Affected Products
- Netcore NAP930 router
- Firmware version 0.1.241010.141410
- Network Tools CGI component (/www/cgi-bin/network_tools)
Discovery Timeline
- 2026-09-29 - CVE-2026-102240 published to NVD
- 2026-09-29 - Last updated in NVD database
Technical Details for CVE-2026-102240
Vulnerability Analysis
The vulnerability is classified under CWE-77: Improper Neutralization of Special Elements used in a Command. The affected CGI script /www/cgi-bin/network_tools implements network diagnostic functionality (typically ping, traceroute, or DNS lookup features) commonly exposed in consumer router web interfaces.
The script passes the user-supplied sid parameter into an eval construct without sanitization. Because eval interprets its argument as shell code, injected metacharacters such as ;, |, &&, or backticks execute as separate commands. The attack requires no authentication and no user interaction, and it can be launched over the network against the router's web management interface.
Successful exploitation grants command execution in the context of the CGI process, which on embedded routers typically runs as root. This yields full device control, including configuration tampering, DNS hijacking, firmware modification, and credential theft.
Root Cause
The root cause is the direct concatenation of the untrusted sid HTTP parameter into a shell command evaluated by the CGI handler. The developer relied on eval semantics without applying input validation, allow-listing, or safe argument passing. No neutralization of shell metacharacters occurs before the command reaches the operating system shell.
Attack Vector
An unauthenticated remote attacker sends a crafted HTTP request to the /www/cgi-bin/network_tools endpoint, supplying a malicious sid value containing shell metacharacters. The injected payload executes on the router. Where the management interface is exposed to the WAN, exploitation is fully remote; on LAN-only deployments, an attacker with local network access or a cross-site request can trigger execution. Technical exploitation notes are available in the public write-up on GitHub and VulDB CVE-2026-102240.
Stop Remote Code Execution Before It Runs
Singularity™ Endpoint detects and blocks exploit attempts at machine speed, including zero-days and novel attack techniques.
Stop Exploit AttemptsDetection Methods for CVE-2026-102240
Indicators of Compromise
- HTTP requests to /www/cgi-bin/network_tools containing shell metacharacters (;, |, &, `, $() in the sid parameter.
- Unexpected outbound connections from the router to attacker-controlled hosts, including reverse shells or download attempts using wget, curl, or tftp.
- New or modified files under /tmp, /var, or persistent storage on the router filesystem.
- Unauthorized changes to DNS servers, firewall rules, or administrative credentials on the device.
Detection Strategies
- Inspect web server and CGI access logs on the router for anomalous sid values that include command separators or URL-encoded shell characters.
- Deploy network intrusion detection signatures matching command-injection payload patterns against traffic destined for router management interfaces.
- Monitor DNS and NetFlow telemetry for routers initiating unusual outbound connections, particularly to non-ISP infrastructure.
Monitoring Recommendations
- Alert on any HTTP POST or GET to network_tools originating from WAN-side IP addresses.
- Track configuration drift on managed edge devices using baseline comparisons.
- Correlate authentication anomalies on downstream systems with router activity to identify pivot attempts.
How to Mitigate CVE-2026-102240
Immediate Actions Required
- Disable remote (WAN) administration on the Netcore NAP930 immediately and restrict web management access to trusted LAN hosts only.
- Place affected routers behind an upstream firewall that blocks inbound access to HTTP management ports.
- Rotate all administrative credentials and review router configuration for unauthorized changes.
- Inventory the environment to identify any Netcore NAP930 devices running firmware 0.1.241010.141410.
Patch Information
No vendor patch is available. According to the disclosure, Netcore was contacted before publication but did not respond. Organizations should treat affected devices as unpatched and plan replacement with a supported router platform where feasible. Track vendor communications through VulDB Vulnerability #411139 for any updates.
Workarounds
- Block external access to the router's web management interface at the perimeter.
- Segment router management VLANs from user and server networks to limit blast radius.
- Filter inbound requests to /www/cgi-bin/network_tools at an upstream reverse proxy or web application firewall if the interface must remain reachable.
- Consider replacing the device with a vendor-supported alternative given the absence of vendor response.
# Example upstream firewall rule to block WAN access to router HTTP management
iptables -I FORWARD -p tcp -d <router_ip> --dport 80 -i <wan_interface> -j DROP
iptables -I FORWARD -p tcp -d <router_ip> --dport 443 -i <wan_interface> -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
