CVE-2026-73163

Executive Summary

CVE-2026-73163 is an OS command injection vulnerability (CWE-78) in the web management interface of the Advantech EKI-1242IEIMS industrial Ethernet switch running firmware version V1.06.01. A remote, authenticated attacker can supply crafted request parameters to a web interface function that improperly neutralizes shell metacharacters, resulting in arbitrary OS command execution with root privileges. Because the affected device is an industrial network component, successful exploitation yields complete compromise of the device and potentially provides a pivot point into the OT/ICS network segment it serves.

Technical Analysis

The vulnerability is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'). According to the NVD description (source: Nozomi Networks Labs), the flaw resides in the web management interface of the Advantech EKI-1242IEIMS. The device is reachable through that interface, and the vulnerable code path passes attacker-controlled request parameters to an underlying operating-system command without sufficient sanitization or escaping of shell metacharacters.

At the mechanism level, OS command injection of this class typically occurs when a web application constructs a shell command string by concatenating user-supplied input — for example, a parameter used to select a network tool, set a system value, or invoke a diagnostic routine — and then executes it through a shell interpreter. If the application does not neutralize special elements such as ;, |, &, $(), or backticks, an authenticated user can append or substitute additional commands. The NVD description explicitly states that the crafted request parameters allow arbitrary OS commands to be executed as root, confirming both the injection primitive and the privilege level obtained.

The description does not identify specific parameter names, endpoint paths, or function names, and no public PoC or Nuclei template is available. Accordingly, the exact injection point is not disclosed. What is certain from the advisory is: (a) the attack surface is the web management interface, (b) authentication is required (remote authenticated attacker), (c) the impact is command execution at root, and (d) the affected firmware is V1.06.01. No information is available regarding stack protections, service accounts, or command-context details beyond the root outcome.

The affected product family — Advantech EKI series managed industrial Ethernet switches — is commonly deployed at the edge of OT networks to provide connectivity and management for PLCs, RTUs, HMIs, and other industrial devices. The web management interface is typically exposed on the management VLAN or, in misconfigured deployments, directly to corporate or internet-reachable interfaces.

Exploitation Scenarios

No public PoC is available; the attack chain below is inferred from the vulnerability class and the facts stated in the NVD description.

1. Reconnaissance and target identification. The attacker identifies reachable Advantech EKI-1242IEIMS devices, typically by scanning for the web management interface over HTTP/HTTPS (TCP 80/443) and fingerprinting the login page or product banners. Shodan queries such as http.title:"EKI" or http.html:"Advantech" can locate exposed instances. The attacker must also possess valid credentials or obtain them through other means (default credentials, credential reuse, phishing, or prior compromise), because exploitation requires authentication.

2. Triggering the flaw class. After authenticating to the web management interface, the attacker locates the request that reaches the vulnerable command-construction code path. Because the vulnerability is an OS command injection, the attacker submits crafted request parameters containing shell metacharacters alongside a command payload. The application fails to neutralize these characters and passes them into an OS command invocation.

3. Payload/execution at the vulnerability-class level. The injected metacharacters cause the underlying shell to interpret the attacker's input as an additional command. The NVD description confirms that resulting commands execute as root, meaning the payload runs with the highest privilege on the device operating system. Typical payload classes for this stage include command chaining (;, &&, |) to run diagnostic or file operations, and reverse-shell or downloader commands to establish interactive control.

4. Post-exploitation impact. With root-level command execution, the attacker can read or modify device configuration, alter network routing and switching behavior, exfiltrate credentials or configuration data, install persistence, and pivot to any device on the OT network segment reachable through the switch. Because the compromised device is a network infrastructure element, the attacker may also intercept or redirect traffic, enabling man-in-the-middle operations against industrial protocols.

Impact Assessment

The vulnerability allows a remote authenticated attacker to obtain root-level OS command execution on the affected device. The CVSS vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H reflects: network-exploitable (AV:N), low attack complexity (AC:L), requires low privileges (PR:L, consistent with the "authenticated" requirement), no user interaction (UI:N), and a changed scope (S:C) — meaning exploitation of the switch can impact resources beyond the vulnerable component itself (i.e., other hosts on the network). Confidentiality, integrity, and availability impacts are all High.

Business impact centers on the OT/ICS environment: the EKI-1242IEIMS is a managed industrial switch, so root compromise can disrupt industrial process connectivity, corrupt or redirect control traffic, and serve as a beachhead for lateral movement deeper into the OT network. The blast radius extends beyond the device to every system relying on it for connectivity. Availability impact is high because an attacker can disable interfaces, reboot the device, or alter switching configuration. Because the exploit requires authentication, the practical risk is elevated in environments with weak or default credentials, shared management accounts, or exposed management interfaces.

Detection Guidance

Sigma Rule

title: Potential OS Command Injection Against Advantech EKI-1242IEIMS Web Interface
id: 7f3c9a12-4b6e-4d21-9c88-2a1f6e0b5d47
status: experimental
description: Detects HTTP requests to the Advantech EKI web management interface containing shell metacharacters indicative of CWE-78 OS command injection attempts.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-73163
author: valtersit.com
date: 2026-01-01
logsource:
  category: webserver
  product: advantech
detection:
  selection_method:
    cs-method:
      - POST
      - GET
  selection_uri:
    cs-uri-stem|contains:
      - '/cgi-bin/'
      - '/goform/'
      - '/cgi/'
  selection_payload:
    cs-uri-query|contains:
      - ';'
      - '|'
      - '&&'
      - '$('
      - '`'
      - '/bin/sh'
      - 'wget '
      - 'curl '
      - 'nc '
  condition: selection_method and selection_uri and selection_payload
falsepositives:
  - Legitimate administrative input containing shell-like characters
level: high
tags:
  - attack.t1190
  - cwe.78

YARA Rule

rule CVE_2026_73163_Advantech_EKI_CMDi
{
    meta:
        description = "Detects shell metacharacter patterns associated with CVE-2026-73163 OS command injection against Advantech EKI web interface logs and captures"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-73163"
        date = "2026-01-01"
        cwe = "CWE-78"
    strings:
        $metachar1 = ";cat /etc/passwd"
        $metachar2 = "|whoami"
        $metachar3 = "$(id)"
        $metachar4 = "`id`"
        $metachar5 = ";wget http"
        $metachar6 = ";curl http"
        $metachar7 = "&&reboot"
        $metachar8 = ";nc -e"
        $method = "POST"
    condition:
        uint16(0) == 0x4854 or
        (any of ($metachar*) and $method)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-73163 Advantech EKI Web Interface OS Command Injection Attempt"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/cgi"; http.request_body; content:";"; http.request_body; content:"cat /etc/passwd"; sid:202673163; rev:1; reference:cve,2026-73163; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-73163; classtype:web-application-attack; metadata:created_at 2026_01_01, updated_at 2026_01_01;)

Elastic Detection

sequence by source.ip with maxspan=30s
  [network where http.request.method == "POST" and
     url.path : ("/cgi-bin/*", "/goform/*", "/cgi/*")]
  [network where http.request.body.content : ("*;*", "*|*", "*$(*", "*`*") and
     http.request.body.content : ("*cat*", "*wget*", "*curl*", "*nc *", "*sh *")]

Splunk SPL Query

index=web OR index=proxy sourcetype=access_combined
| eval raw=urldecode(uri_query)." ".urldecode(form_data)
| where match(raw, ";|\\||&&|\\$\\(|`")
| where match(raw, "(cat|wget|curl|nc|chmod|reboot|/bin/sh)")
| where match(uri_path, "(?i)(cgi-bin|goform|cgi)")
| stats count min(_time) as first_seen max(_time) as last_seen values(src_ip) as sources by uri_path, raw
| sort -count

Wazuh OSSEC Rule

<group name="advantech,web,web_appsec,">
  <rule id="2026001" level="12">
    <decoded_as>json</decoded_as>
    <match>cgi-bin|goform|cgi</match>
    <regex>;|\\||&&|\\$\\(|`</regex>
    <description>CVE-2026-73163: Potential OS command injection attempt against Advantech EKI web management interface</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>cwe_78,attack,</group>
  </rule>
  <rule id="2026002" level="14">
    <decoded_as>json</decoded_as>
    <regex>(cat /etc/passwd|wget http|curl http|nc -e|/bin/sh)</regex>
    <description>CVE-2026-73163: High-confidence OS command injection payload detected on Advantech EKI device</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>cwe_78,attack,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). No vendor fix or workaround is currently documented for firmware V1.06.01.

1. Immediate mitigations:

   • Remove the web management interface from untrusted networks. Place it behind an isolated management VLAN and firewall, allowing only trusted administrator hosts.
   • Enforce strong, unique credentials for the web interface; eliminate default and shared accounts. Exploitation requires authentication, so credential hygiene directly reduces risk.
   • Apply network ACLs to restrict access to TCP 80/443 on the device to authorized management addresses only.
   • Enable logging and forward web interface access logs to a central SIEM so that injection attempts are detected even before a patch exists.
   • Monitor for anomalous device behavior (unexpected reboots, configuration changes, egress traffic from the switch).

2. Patch/upgrade steps:

   • No patch is currently available. Monitor Advantech's security advisory channel and the Nozomi Networks Labs disclosure for a fixed firmware release.
   • When a fixed firmware image is published, validate it against the vendor's checksum/signature and apply it during a maintenance window, as the device is likely inline in OT connectivity.
   • Track the CVE record at NVD for authoritative updates on affected and fixed versions.

3. Long-term hardening:

   • Adopt a vulnerability management program that covers OT/IoT devices, including the Advantech EKI product line and its dependencies.
   • Enforce least privilege for device management roles and disable unused services.
   • Segment OT networks from IT and the internet; require a jump host for all device administration.
   • Establish a firmware lifecycle process that tracks vendor advisories (Nozomi Networks Labs, CISA ICS advisories) and schedules updates.

References

• NVD — CVE-2026-73163: https://nvd.nist.gov/vuln/detail/CVE-2026-73163
• Nozomi Networks Labs (reporter per NVD description): https://www.nozominetworks.com/labs
• Advantech Product Security: https://www.advantech.com/en-eu/support/security-advisory
• CISA ICS Advisories (for Advantech product coverage): https://www.cisa.gov/ics-advisories
• CWE-78 — Improper Neutralization of Special Elements used in an OS Command: https://cwe.mitre.org/data/definitions/78.html

No threat actor campaigns or exploit-in-the-wild evidence are currently known for CVE-2026-73163. CVE is not listed in CISA KEV, no PoC or exploit code is public, and no Nuclei template exists.