CVE-2026-102240

Executive Summary

CVE-2026-102240 is a critical OS command injection vulnerability in the Netcore NAP930 wireless access point, specifically within the Network Tools CGI component at /www/cgi-bin/network_tools, where the sid argument is passed unsanitized to an eval call. With a CVSS 3.1 base score of 10.0 and a public exploit already available, any unauthenticated remote attacker who can reach the device's web management interface can achieve full command execution as the underlying service account. Because the vulnerability is network-reachable, requires no privileges or user interaction, and the vendor has not issued a patch or responded to disclosure, affected deployments remain fully exposed until compensating controls are applied or the device is removed from production networks.

Technical Analysis

The affected product is the Netcore NAP930, an enterprise/ISP-class wireless access point. The vulnerable firmware build is 0.1.241010.141410. The flaw resides in the Network Tools CGI handler implemented in the file /www/cgi-bin/network_tools.

According to the NVD description, the vulnerability is an OS command injection (CWE-77) in which manipulation of the sid argument is passed into an eval construct. The use of eval in a CGI context is the central design flaw: rather than constructing a bounded system call with a fixed command and separately validated parameters, the handler evaluates attacker-influenced input, allowing shell metacharacters and command substitution to be interpreted by the underlying shell. The sid parameter is therefore the primary injection point.

Attack surface:

• Vector: Network (remote), over the web management/HTTP interface exposed by the device.
• Authentication: Not required (PR:N), meaning the endpoint is reachable and exploitable without valid credentials — consistent with the CGI endpoint being callable directly.
• User interaction: None (UI:N).
• Scope change: The CVSS vector declares a Scope change (S:C), reflecting that the exploited CGI process can affect resources beyond its original security authority — i.e., arbitrary command execution on the embedded OS rather than confinement to the web service.

Because the description provides no further implementation detail beyond the file path, component name, function (eval), and parameter (sid), no additional code-level claims (specific quoting characters, exact shell invocation, or additional parameters) should be assumed. The class of attack — command injection via evaluated input in a CGI handler — is well understood and frequently results in complete device compromise on embedded networking hardware.

Exploitation Scenarios

The following attack chain is derived strictly from the NVD description and the vulnerability class (CWE-77). No public PoC code was provided; the steps below describe the vulnerability class and mechanism, not a fabricated implementation.

1. Reconnaissance / target identification An attacker scans for exposed Netcore NAP930 management interfaces. Targets are identified by their web management interface hosting the CGI component at /cgi-bin/network_tools. Because the CVSS vector indicates no privileges or user interaction are required, an accessible interface is sufficient — no login is presumed necessary.

2. Triggering the flaw The attacker sends a crafted request to the Network Tools CGI handler that supplies a malicious value in the sid argument. Because the argument is evaluated by the eval construct in /www/cgi-bin/network_tools, shell metacharacters within the sid value are interpreted rather than treated as inert data, resulting in command injection.

3. Payload / execution (vulnerability-class level) At the class level, the attacker embeds OS command syntax inside the sid parameter so that the evaluated expression executes an arbitrary command on the device. The exact delimiter and encoding are not specified in the available data; the defining characteristic is that sid reaches eval without adequate sanitization.

4. Post-exploitation impact Successful injection yields arbitrary command execution on the access point's embedded OS. Given Scope:C, Confidentiality:H, Integrity:H, and Availability:H, an attacker can read sensitive configuration and credentials, modify device and network configuration, pivot into the adjacent network, or render the device unavailable. As an access point, compromise can also enable traffic interception on the wireless segment.

No public exploit code is bundled with this report; the chain above is inferred from the vulnerability class and the description provided. The NVD entry states the exploit has been made public and "could be used," indicating active risk of weaponization even where tailored tooling is not yet widely distributed.

Impact Assessment

• CVSS 3.1 Base: 10.0 (Critical) — AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.
• Attack Vector Network / Complexity Low / No Privileges / No Interaction: trivial to trigger from any host with reachability to the management interface.
• Scope Changed: impact extends beyond the CGI process authority to the entire device.
• Confidentiality/Integrity/Availability: all High — full device compromise.
• Blast radius: each affected NAP930 is fully compromisable; as a network edge device, a compromised AP can serve as a foothold for lateral movement and man-in-the-middle activity on connected segments.
• Exposure: EPSS has not yet been scored by FIRST.org, so no probabilistic exploitation estimate is available; however, the presence of a public exploit and the unpatched status elevate real-world risk.
• CISA KEV: Not listed.

Detection Guidance

Sigma Rule

title: Netcore NAP930 network_tools OS Command Injection via sid
id: 3b6f9c2a-netcore-nap930-cmdinj
status: experimental
description: Detects attempts to exploit command injection in the Netcore NAP930 network_tools CGI (CVE-2026-102240)
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-102240
author: valtersit.com
logsource:
  category: webserver
detection:
  selection_uri:
    cs-uri-stem|contains:
      - '/cgi-bin/network_tools'
  selection_meta:
    cs-uri-query|contains:
      - ';'
      - '|'
      - '`'
      - '$('
      - '&&'
      - 'sid='
  condition: selection_uri and selection_meta
fields:
  - c-ip
  - cs-uri
  - cs-uri-query
  - sc-status
falsepositives:
  - Legitimate administrative traffic containing shell metacharacters (rare)
level: critical

YARA Rule

rule CVE_2026_102240_Netcore_NAP930_NetworkTools_CmdInj
{
    meta:
        description = "Detects Netcore NAP930 network_tools CGI abused for OS command injection"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-102240"
        cve = "CVE-2026-102240"
        author = "valtersit.com"
        date = "2026-01-01"
        severity = "critical"

    strings:
        $cgi = "/www/cgi-bin/network_tools" ascii
        $sid = "sid=" ascii nocase

    condition:
        $cgi or ($sid and filesize < 500KB)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-102240 Netcore NAP930 network_tools CGI OS Command Injection (sid)"; flow:established,to_server; http.uri; content:"/cgi-bin/network_tools"; http.uri; content:"sid="; pcre:"/(?:;|\||`|\$\(|%3B|%7C|%60|%24%28)/Ui"; classtype:web-application-attack; reference:cve,2026-102240; sid:2026102240; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=10s
  [network where http.request.method == "GET" and url.path : "/cgi-bin/network_tools"]
  [network where url.query : ("sid=" and (";" or "|" or "`" or "$(" or "&&"))]

Splunk SPL Query

index=web OR index=proxy
| eval uri=coalesce(uri, url, cs_uri)
| where like(uri, "%/cgi-bin/network_tools%")
| where match(uri, "(?i)(sid=.*(;|\||`|\$\(|&&))")
| stats count min(_time) as first_seen max(_time) as last_seen by src_ip, uri, status
| sort - count

Wazuh OSSEC Rule

<group name="web,netcore,cve-2026-102240,">
  <rule id="100240" level="15">
    <decoded_as>web-accesslog</decoded_as>
    <id>31100</id>
    <match>/cgi-bin/network_tools</match>
    <regex>sid=.*(;|\||`|\$\(|&&)</regex>
    <description>CVE-2026-102240: Netcore NAP930 network_tools OS command injection attempt (sid)</description>
    <mitre>
      <id>T1190</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). The vendor was contacted early about this disclosure but did not respond, and no vendor advisory, fixed firmware, or workaround is available.

1. Immediate mitigations

   • Remove or isolate affected Netcore NAP930 devices from untrusted network exposure. Do not expose the web management interface to the internet or to guest/untrusted VLANs.
   • Restrict management access via firewall/ACLs to a dedicated, authenticated administrative network; permit only known management IPs.
   • Disable the Network Tools feature/management CGI if the management interface supports it, or block requests to /cgi-bin/network_tools at the perimeter/WAF.
   • Enforce strong network segmentation so that compromise of an AP cannot reach management, authentication, or data plane segments (limits the Scope:C impact).
   • Monitor for anomalous outbound traffic from the device and for inbound requests targeting the vulnerable endpoint.

2. Patch/upgrade steps

   • No patch is available. Continue monitoring for a vendor firmware update; engage Netcore support/security directly and reference CVE-2026-102240 and firmware build 0.1.241010.141410.
   • If the vendor remains unresponsive and risk cannot be mitigated in place, plan replacement of the affected devices.

3. Long-term hardening

   • Adopt a hardware/software inventory and vulnerability management program that includes network appliances and IoT/embedded devices, not just servers.
   • Enforce a lifecycle policy requiring vendor security response commitments; deprecate products whose vendors do not respond to coordinated disclosure.
   • Deploy network detection (Suricata/Wazuh/SIEM rules above) to catch exploitation attempts at perimeter and internal chokepoints.

References

• NVD — CVE-2026-102240: https://nvd.nist.gov/vuln/detail/CVE-2026-102240
• MITRE CWE-77 (Improper Neutralization of Special Elements used in a Command): https://cwe.mitre.org/data/definitions/77.html
• MITRE ATT&CK T1190 — Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
• Vendor (Netcore): no published advisory — vendor did not respond to disclosure
• CISA Known Exploited Vulnerabilities catalog: not listed (as of this report)

No specific threat actor campaign or confirmed in-the-wild exploitation targeting this CVE has been reported in the available data. The NVD description states that a public exploit exists and could be used, which represents a latent exploitation risk pending observed campaigns.