CVE-2026-101001

Executive Summary

CVE-2026-101001 is a critical OS command injection vulnerability in the Netcore NBR200V2 router (version 1.3.241127.071246). The flaw exists in the eval function within the /www/cgi-bin/network_tools CGI script of the web management interface and is triggered via manipulation of the QUERY_STRING argument. An unauthenticated, remote attacker can exploit this vulnerability to execute arbitrary operating system commands on the underlying device, leading to complete compromise of confidentiality, integrity, and availability. The vendor has been contacted but has not responded, and no patch is available.

Technical Analysis

The vulnerability is classified as CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection'). The NVD description states that the issue impacts the eval function of the file /www/cgi-bin/network_tools within the Web Management Interface component. The manipulation of the argument QUERY_STRING leads to OS command injection.

From a technical standpoint, the eval function in the context of a CGI script or shell environment typically parses and executes its input as code or commands. The QUERY_STRING environment variable contains the raw query string portion of an HTTP request URL. When this variable is passed to eval without proper sanitization, an attacker can inject shell metacharacters (such as ;, |, &, or $()) to break out of the intended command context and execute arbitrary system commands.

The attack surface is the web management interface exposed by the device, specifically the /www/cgi-bin/network_tools endpoint. Because the vulnerability allows remote, unauthenticated exploitation (as indicated by the CVSS vector AV:N/PR:N/UI:N), no credentials are required to trigger the flaw. The CVSS scope change (S:C) indicates that a compromise of the vulnerable component impacts resources beyond its security scope, meaning full device compromise can lead to lateral movement within the network.

The CVSS score is 10.0 (Critical), reflecting the maximum impact across confidentiality, integrity, and availability. The EPSS score is not yet available, and there is no CISA KEV entry, but the NVD description explicitly notes that "the exploit is publicly available and might be used," elevating the urgency for defenders.

Exploitation Scenarios

Based on the NVD description and the vulnerability class, the attack chain is as follows:

1. Reconnaissance/Target Identification: An attacker scans the internet or local network for Netcore NBR200V2 devices with the web management interface exposed. Shodan or similar tools can identify devices via HTTP response keywords such as "NBR200V2" or the management interface title. The device's version (1.3.241127.071246) can be fingerprinted from the login page or HTTP headers.

2. Triggering the Flaw: The attacker sends a crafted HTTP request to the /www/cgi-bin/network_tools CGI script. The request includes a malicious payload in the query string (the QUERY_STRING parameter). Because the script passes QUERY_STRING directly to the eval function without sanitization, shell metacharacters injected into the query string are executed by the underlying operating system.

3. Payload/Execution Method: At the vulnerability-class level, the attacker would use command separators (e.g., ;, |, &&) followed by an arbitrary OS command. For example, a request such as GET /cgi-bin/network_tools?;id would cause the id command to execute if the injection is successful. The specific payload syntax depends on the exact parsing logic, but the principle of OS command injection applies: the attacker escapes the intended command context and runs arbitrary commands with the privileges of the CGI process (typically root on embedded devices).

4. Post-Exploitation Impact: Successful exploitation grants the attacker full control over the device. They could:

   • Exfiltrate sensitive data (configuration files, credentials, network topology).
   • Modify device settings (DNS, routing, firewall rules) to redirect traffic or establish persistence.
   • Use the device as a pivot point to attack other systems on the internal network.
   • Deploy malware or botnet clients (e.g., Mirai variants).
   • Cause a denial of service by rebooting or bricking the device.

No public PoC is available in the provided data, but the NVD description explicitly states that "the exploit is publicly available and might be used." The attack chain is inferred from the vulnerability class and the described parameters.

Impact Assessment

The impact of CVE-2026-101001 is critical. With a CVSS base score of 10.0, the vulnerability allows a remote, unauthenticated attacker to fully compromise the device. The scope change (S:C) indicates that the compromise can affect other systems beyond the router itself, such as internal network hosts. The high confidentiality, integrity, and availability impacts mean that all aspects of the device's security are at risk.

Affected systems are Netcore NBR200V2 routers running firmware version 1.3.241127.071246. These devices are typically deployed in small office/home office (SOHO) environments, branch offices, or as edge routers. The blast radius includes any network segment that the router serves. An attacker who compromises the router can intercept or manipulate all traffic passing through it, leading to potential data breaches, man-in-the-middle attacks, or further network intrusion.

Given the public exploit availability and the lack of a vendor patch, the risk is extremely high. The EPSS score is not yet available, but the public exploit status suggests a high likelihood of active exploitation in the wild.

Detection Guidance

Sigma Rule

title: Netcore NBR200V2 OS Command Injection Attempt
id: 5f8c3a2b-1d4e-4f7a-9b2c-8e6d5a3c1b2f
status: experimental
description: Detects attempts to exploit CVE-2026-101001 via the /www/cgi-bin/network_tools endpoint by identifying command injection characters in the QUERY_STRING.
author: Threat Intelligence Team
date: 2026-01-15
logsource:
  category: webserver
  product: netcore
detection:
  selection:
    cs-method: 'GET'
    cs-uri-stem: '/cgi-bin/network_tools'
    cs-uri-query|contains:
      - ';'
      - '|'
      - '&&'
      - '`'
      - '$('
      - '$(('
  condition: selection
falsepositives:
  - Legitimate administrative scripts that use these characters in query strings (unlikely)
level: critical

YARA Rule

rule CVE_2026_101001_Netcore_Command_Injection
{
    meta:
        description = "Detects exploitation attempts of CVE-2026-101001 in HTTP requests targeting Netcore NBR200V2"
        author = "Threat Intelligence Team"
        date = "2026-01-15"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-101001"
        severity = "critical"
    strings:
        $s1 = "/cgi-bin/network_tools" ascii wide nocase
        $s2 = "QUERY_STRING" ascii wide nocase
        $cmd1 = ";" ascii
        $cmd2 = "|" ascii
        $cmd3 = "&&" ascii
        $cmd4 = "$(" ascii
        $cmd5 = "`" ascii
    condition:
        any of ($s1, $s2) and any of ($cmd*)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-101001 Netcore NBR200V2 OS Command Injection Attempt"; flow:to_server,established; content:"/cgi-bin/network_tools"; http_uri; nocase; pcre:"/(;|\||&&|\$\(|`)/U"; reference:cve,2026-101001; reference:url,https://nvd.nist.gov/vuln/detail/CVE-2026-101001; classtype:attempted-admin; sid:10000001; rev:1;)

Elastic Detection

sequence by host.id with maxspan=5s
  [network where network.protocol == "http" and
   http.request.method == "GET" and
   url.path == "/cgi-bin/network_tools" and
   url.query contains ";" or url.query contains "|" or url.query contains "&&" or url.query contains "$(" or url.query contains "`"]

Splunk SPL Query

index=web OR index=proxy
sourcetype=access_combined OR sourcetype=pan:traffic
method=GET uri_path="/cgi-bin/network_tools"
| regex uri_query="(;|\||&&|\$\(|`)"
| stats count by src_ip, uri_query, user_agent, status
| where count > 0
| sort - count

Wazuh OSSEC Rule

<group name="web,netcore,">
  <rule id="100100" level="12">
    <if_sid>31100</if_sid>
    <id>^/cgi-bin/network_tools</id>
    <url>;</url>
    <description>CVE-2026-101001: Netcore NBR200V2 OS command injection attempt detected in QUERY_STRING</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>cve_2026_101001,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1. Immediate Mitigations:

   • Disable the web management interface on the WAN side if not required. Restrict access to the management interface to trusted internal IP addresses only via firewall rules.
   • If remote management is necessary, place the device behind a VPN and enforce strong authentication.
   • Monitor network traffic for exploitation attempts using the provided detection rules.
   • Consider replacing affected devices with alternative router models if the vendor remains unresponsive.

2. Patch/Upgrade Steps:

   • No patch is available. The vendor (Netcore) was contacted but did not respond. Users should check the vendor's website periodically for firmware updates and apply them as soon as they become available.
   • If a patch is released, upgrade to the latest firmware version following the vendor's instructions.

3. Long-term Hardening:

   • Implement network segmentation to isolate IoT and embedded devices from critical assets.
   • Use egress filtering to prevent compromised devices from communicating with command-and-control servers.
   • Regularly audit firmware versions and replace end-of-life devices.
   • Deploy intrusion detection/prevention systems (IDS/IPS) with up-to-date signatures.
   • Conduct regular vulnerability scans to identify unpatched devices.

References

• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-101001
• CWE-77: https://cwe.mitre.org/data/definitions/77.html
• MITRE ATT&CK T1190: https://attack.mitre.org/techniques/T1190/
• Vendor Advisory: None available (vendor did not respond)
• CISA KEV: Not listed as of report date.