CVE-2026-24444: SDMC NE6037 Hardcoded Credentials Root Access Vulnerability

Technical summary

The vulnerability stems from the presence of a hardcoded credential embedded in the firmware of SDMC NE6037 devices running versions 7.1.6.0.25 and 7.1.6.1.9_B9. The web management interface exposes recovery endpoints (mgmt.php and npcmd.php) that accept this hardcoded password for authentication. These endpoints are accessible without prior authentication, and successful submission of the hardcoded credential grants root privileges. The vulnerability is classified as CWE-798 (Use of Hardcoded Credentials), which represents a fundamental authentication bypass. The network-accessible nature of the web interface means exploitation requires only network connectivity—no user interaction, local access, or system complexity is needed. An attacker can then leverage root access to enable additional services such as filtered SSH and Telnet, expanding the attack surface and enabling deeper system compromise.

Business impact

This vulnerability represents a complete loss of confidentiality, integrity, and availability for any affected SDMC NE6037 device on your network. Cable modem routers serve as perimeter security devices and gateways for internet connectivity; their compromise grants attackers direct access to the network boundary. Attackers can intercept, modify, or block all internet traffic flowing through the compromised modem, potentially affecting every downstream device. They can also pivot from the modem into your internal network, install persistent backdoors, exfiltrate data, or use the device as a launching point for attacks against other systems. In enterprise or managed service provider environments, a single compromised modem can expose entire customer networks. The presence of hardcoded credentials suggests a fundamental product security issue that may require complete replacement or extensive mitigation, not merely patching.

Affected systems

SDMC NE6037 cable modem routers running firmware versions 7.1.6.0.25 and 7.1.6.1.9_B9 are explicitly vulnerable. Organizations should verify whether they have deployed this specific model and check firmware versions against the affected versions listed. ISP customers who received this modem as their primary gateway are particularly exposed. The provided data does not list additional affected SDMC product models or firmware versions, so verification against the vendor advisory is essential to determine the full scope of exposure within your environment.

Exploitability

This vulnerability presents extremely high exploitability because it requires no authentication, no user interaction, and no special system knowledge. The attack is entirely network-based and can be executed remotely by any attacker with basic HTTP client capability—a simple curl command or web browser suffices. The hardcoded credential is static and will not change between devices of the same firmware version, meaning the attack scales trivially across all affected units. No special tools or zero-day research are required; this is a straightforward credential submission attack. The critical CVSS score of 9.8 reflects these factors: network accessibility (AV:N), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction (UI:N). Given the internet-facing nature of cable modem management interfaces, exploitation can occur immediately and continuously. The vulnerability is not currently listed on the CISA KEV catalog, but the lack of KEV status does not reduce the genuine risk—it reflects only current exploitation tracking, not severity or exploitability.

Remediation

Immediate patching is the primary remediation. Verify the current firmware version of affected SDMC NE6037 devices and confirm availability of a patched firmware version that addresses this hardcoded credential vulnerability. Firmware updates should be applied as soon as vendor patches are released; defer other non-critical maintenance to prioritize this critical fix. Until patching is complete, enforce compensating controls: restrict access to the web management interface (mgmt.php, npcmd.php endpoints) to trusted administrative networks only, disable web management from the WAN side if possible, and isolate affected modems from untrusted networks. Change any default credentials or recovery accounts if the device supports manual credential modification. Monitor for suspicious access to management endpoints and for unexpected enablement of SSH or Telnet services on affected devices. Given the severity, prioritize patching for all affected units within days, not weeks.

Patch guidance

Consult the SDMC vendor advisory and product support portal for patched firmware versions that address CVE-2026-24444. Verify the published patch versions against your device's current firmware build (accessible via the web management interface or device settings). Firmware updates for cable modems are typically deployed via the ISP network or can be manually downloaded and applied. Coordinate with your ISP if you are a residential or small business customer, as firmware updates may be pushed automatically; do not assume your device will be auto-updated immediately. For managed deployments, validate patch applicability against your specific firmware version before bulk rollout. After patching, reboot the device and verify that the hardcoded credential no longer grants access to recovery endpoints. Re-enable web management security features and restore normal access control policies.

Detection guidance

Monitor network logs for HTTP requests to the web management endpoints (mgmt.php and npcmd.php) on affected SDMC modem devices, particularly requests originating from untrusted sources or from outside your network. Inspect request payloads for submission of the hardcoded credential (specific credential identifier should be referenced in the vendor advisory). On the device itself, check system logs for successful root-level authentication or unexpected privilege escalation events. Monitor for unexpected enablement of SSH (port 22) or Telnet (port 23) services, which may indicate post-exploitation activity. Implement network-based alerting for suspicious access to cable modem management interfaces, and segment modem management traffic to prevent unauthorized access paths. Consider deploying endpoint detection tools on systems downstream of affected modems to detect lateral movement or data exfiltration resulting from modem compromise.

Why prioritize this

This vulnerability merits immediate prioritization because it combines critical severity (CVSS 9.8) with trivial exploitability and network accessibility. The hardcoded credential cannot be changed without a firmware update, and the recovery endpoints are inherently accessible to any network-connected attacker. Cable modem routers function as security perimeter devices; their compromise directly exposes your network boundary and enables pivoting attacks into internal systems. The lack of any authentication requirement, attack complexity, or user interaction means this vulnerability will be actively exploited as soon as attackers discover or release the hardcoded credential publicly. Delaying patching increases the window of exposure substantially. Organizations should treat this as a P0 or P1 incident and allocate resources immediately to patch affected devices.

Risk score, explained

The CVSS 3.1 score of 9.8 (CRITICAL) reflects the complete loss of confidentiality, integrity, and availability resulting from unauthenticated root access via a network-accessible interface. The vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H indicates: (1) Network Attack Vector—the vulnerability is reachable from the internet without physical access; (2) Low Attack Complexity—no special conditions or timing are required; (3) No Privileges Required—attackers need not be authenticated or logged in; (4) No User Interaction—the attack succeeds without social engineering or user action; (5) Unchanged Scope—the impact is limited to the affected device, not other systems directly (though lateral movement is possible post-exploitation). The three maximum impact ratings (C:H, I:H, A:H) reflect the attacker's ability to read any data (confidentiality), modify system behavior (integrity), and disable the device or its functions (availability). This score appropriately conveys that the vulnerability is exploitable by any attacker and results in complete system compromise.

Frequently asked questions