CVE-2026-4840 is an OS command injection vulnerability discovered in the Netcore Power 15AX router series, specifically affecting firmware versions up to 3.0.0.6938. The vulnerability resides in the setTools function of the /bin/netis.cgi script, part of the device's Diagnostic Tool Interface. By manipulating the IpAddr parameter, an attacker can inject arbitrary operating system commands that the device executes with elevated privileges. This flaw allows remote attackers to execute commands without requiring authentication or user interaction, significantly lowering the barrier to exploitation. The vulnerability was responsibly disclosed to the vendor, but no patch or mitigation has been provided, and a public exploit has been released, increasing the likelihood of active exploitation. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no authentication required (AT:N), no user interaction (UI:N), and high impact on confidentiality, integrity, and availability (VC:H/VI:H/VA:H). This means attackers can fully compromise the device remotely, potentially gaining control over network traffic, stealing sensitive data, or disrupting network operations. The absence of vendor response and patch availability heightens the urgency for organizations to implement alternative mitigations. Given the critical role of such devices in enterprise and service provider networks, exploitation could have severe consequences.

The impact of CVE-2026-4840 is significant for organizations using Netcore Power 15AX devices. Successful exploitation allows attackers to execute arbitrary OS commands remotely with elevated privileges, leading to full device compromise. This can result in unauthorized access to sensitive network data, interception or manipulation of network traffic, disruption of network services, and potential pivoting to other internal systems. The vulnerability threatens confidentiality, integrity, and availability of affected networks. Enterprises, ISPs, and critical infrastructure operators relying on these devices face risks of data breaches, service outages, and reputational damage. The public availability of an exploit increases the likelihood of widespread attacks, including automated scanning and exploitation by threat actors. The lack of vendor patching means organizations must rely on network-level defenses and configuration changes to mitigate risk, increasing operational complexity and potential exposure.

1. Immediately isolate affected Netcore Power 15AX devices from untrusted networks to prevent remote exploitation. 2. Restrict access to the device management interfaces, especially the /bin/netis.cgi endpoint, using network segmentation, firewall rules, or VPNs limited to trusted administrators. 3. Employ Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) with custom rules to detect and block suspicious requests targeting the IpAddr parameter in the Diagnostic Tool Interface. 4. Monitor network traffic and device logs for unusual command execution patterns or unexpected system behavior indicative of exploitation attempts. 5. Disable or restrict the Diagnostic Tool Interface if not essential for operations, reducing the attack surface. 6. Engage with Netcore support channels to request official patches or firmware updates and apply them promptly once available. 7. Consider replacing vulnerable devices with alternative hardware if no timely patch is forthcoming. 8. Implement strong network monitoring and incident response procedures to quickly detect and respond to potential compromises. 9. Educate network administrators about the vulnerability and ensure strict adherence to security best practices for device management.