CVE-2026-73164

Executive Summary

CVE-2026-73164 is a CWE-78 OS command injection vulnerability in the web management interface of the Advantech EKI-1242IEIMS industrial Ethernet switch, firmware version V1.06.01. A remote attacker who holds valid credentials can inject arbitrary OS commands through crafted request parameters, and those commands execute with root privileges on the underlying device. Because the affected product is an industrial network device, successful exploitation grants full control of a network-segment boundary component, enabling lateral movement into OT/ICS environments, persistent traffic manipulation, and destructive configuration changes. No public proof-of-concept, Nuclei template, or patch exists as of this report, and the CVE has not been added to CISA KEV.

Technical Analysis

The vulnerability class is OS command injection (CWE-78), defined as the improper neutralization of special elements used in an OS command. Advantech EKI-1242IEIMS devices expose a web management interface used for configuration, monitoring, and administration of the switch. According to the NVD description, this interface accepts request parameters that are passed to an underlying operating system command without adequate sanitization or escaping. The precise parameter names, handler function names, and URL paths are not disclosed in the available advisory data; the analysis below therefore stays at the vulnerability-class level rather than inventing implementation specifics.

The general mechanism for this class in embedded web interfaces is well established: the web server (commonly an embedded HTTP daemon) receives an HTTP request, extracts one or more parameter values, and constructs a shell command string — for example, a system call that wraps a diagnostic, configuration, or file-management utility. If the parameter value is concatenated into that string without allow-list validation, an attacker can supply shell metacharacters (semicolons, pipes, backticks, $() substitution, ampersands, or newline characters) so that the shell interprets part of the input as a separate command. The resulting command executes in the context of the web server process.

Two properties from the advisory materially raise severity. First, the attacker must be authenticated ("remote authenticated attacker"), which means the flaw is not pre-auth. This lowers the likelihood of opportunistic mass exploitation but does not eliminate it: EKI-series devices frequently ship with default administrative credentials, and credential reuse across management networks is common. Second, commands execute "as root." The EKI-1242IEIMS is a Linux-based embedded device; the web daemon runs with sufficient privilege that injected commands inherit root. This eliminates the need for a second local privilege-escalation step and grants complete control over the device operating system, including access to configuration stores, firmware partitions, network stack settings, and any credentials or keys resident on the device.

The affected build is explicitly identified as firmware version V1.06.01. The advisory does not enumerate a broader version range, does not name the vulnerable binary or CGI endpoint, and does not provide the injection point. Analysts should treat V1.06.01 as confirmed vulnerable and treat adjacent firmware revisions as unverified until Advantech publishes an advisory with a version matrix.

From a weakness-taxonomy standpoint, CWE-78 is a child of CWE-77 (Command Injection) and CWE-74 (Injection). The root cause is a failure to separate data from control instructions: user-supplied data reaches a command interpreter without neutralization. Common remediation patterns include avoiding shell invocation entirely (using exec-family calls with argument arrays), strict allow-list validation of parameter values, and dropping privileges from the web daemon so that injected commands cannot inherit root.

No CVSS vector, base score, or EPSS score has been assigned in the data provided. The vector shown in the metadata section of this report is an analytical estimate based on the vulnerability class and the stated constraints (network vector, low complexity, privileges required, scope change due to root-level code execution on the host OS, high confidentiality/integrity/availability impact). It is not an authoritative score and should not be cited as one. No CISA KEV entry, no public exploit code, and no Nuclei template are associated with this CVE.

Exploitation Scenarios

No public PoC is available for CVE-2026-73164; the attack chain below is inferred from the vulnerability class and the constraints stated in the advisory. Specific endpoint names, parameter names, and payload strings are deliberately omitted because they are not present in the source data.

1. Reconnaissance and target identification. An attacker enumerates internet-exposed or internal-network management interfaces belonging to Advantech EKI-series devices. Industrial switches are frequently deployed on flat management VLANs and are discoverable via HTTP title banners, TLS certificate subject fields, or SNMP. Shodan-style queries targeting the device's web interface banner identify candidate hosts. The attacker confirms the device model and, where the interface discloses it, the firmware revision, prioritizing systems running V1.06.01.

2. Authentication. The advisory specifies a "remote authenticated attacker," so the attacker must first obtain valid credentials. Realistic paths include default or factory credentials left unchanged, credentials harvested from prior breaches or phishing, reuse of shared administrative passwords across an OT network, or credentials recovered from an already-compromised jump host. Once authenticated, the attacker has a session capable of submitting requests to the web management interface.

3. Triggering the injection. The attacker sends a crafted HTTP request to a web management function that passes a user-controlled parameter into an OS command. Because the parameter is not properly neutralized, the attacker embeds shell metacharacters so that the interpreter executes an attacker-chosen command in addition to, or instead of, the intended one. The advisory does not disclose which interface function is vulnerable, so the exact parameter and request shape cannot be stated without fabrication.

4. Execution and post-exploitation. Injected commands run as root on the device OS. Because the device is a network switch sitting at a segment boundary, root control enables: reading and modifying the device configuration; creating local accounts or SSH keys for persistence; altering VLAN, routing, or port-mirroring configuration to redirect or copy traffic; exfiltrating stored credentials, certificates, and pre-shared keys; disabling logging or management agents; and using the device as a pivot point to reach downstream OT assets that trust the switch. The attacker may also attempt to install implants in persistent storage or abuse the firmware update path to maintain access across reboots. Integrity and availability of the industrial network are directly at risk, and recovery may require physical access to the device.

Impact Assessment

The blast radius of this vulnerability is defined by the role of the device, not by the number of hosts. An EKI-1242IEIMS is an industrial Ethernet switch; compromising it grants control of a network chokepoint. Downstream effects include:

• Confidentiality: root access exposes on-device configuration, credentials, certificates, and potentially mirrored or buffered network traffic. Estimated impact high (C:H).
• Integrity: an attacker can alter switch configuration, redirect traffic, or manipulate management responses, undermining trust in the network fabric. Estimated impact high (I:H).
• Availability: misconfiguration, disabling of ports, or destructive commands can cause an OT network outage. Estimated impact high (A:H).
• Scope: because command execution occurs on the host OS rather than within the web application's security context, the compromise escapes the originally authorized component. Estimated scope changed (S:C).

Business impact is concentrated in manufacturing, utilities, transportation, and other environments running Advantech industrial networking gear. The attack requires authentication (PR:L) over the network (AV:N) with no user interaction (UI:N) and low complexity (AC:L), which places it within reach of a moderately resourced adversary already present on the management network. The absence of a patch, an assigned CVSS score, and an EPSS estimate means defenders cannot rely on vendor-prioritized remediation timelines; treatment must be driven by internal risk assessment.

Detection Guidance

Detection for this class relies on correlating HTTP request content with process execution on the device. The rules below are written at the vulnerability-class level because the advisory does not disclose parameter names or endpoints. Analysts should tune the HTTP-side patterns to their environment and, where device telemetry is available, forward operating-system command logs to the SIEM.

Sigma Rule

title: Suspicious Shell Metacharacters in Requests to Advantech EKI Web Interface
id: 8f2c1a44-7b0e-4c9a-9d21-3b6e5a7c9d10
status: experimental
description: Detects shell metacharacters in HTTP request URIs or bodies targeting the Advantech EKI web management interface, consistent with CWE-78 OS command injection attempts.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-73164
author: valtersit.com Threat Intelligence
date: 2026/01/01
logsource:
  category: webserver
detection:
  selection_target:
    cs-uri-stem|contains:
      - '/cgi-bin/'
      - '/goform/'
      - '/cgi/'
  selection_meta:
    cs-uri-query|contains:
      - ';'
      - '|'
      - '`'
      - '$('
      - '&&'
      - '||'
  selection_body:
    cs-uri-query|contains:
      - 'wget '
      - 'curl '
      - '/bin/sh'
      - 'nc -'
  condition: selection_target and (selection_meta or selection_body)
falsepositives:
  - Legitimate administrative tooling that encodes shell characters in parameters (rare on embedded switch UIs)
level: high

YARA Rule

rule CVE_2026_73164_Advantech_EKI_Command_Injection
{
    meta:
        description = "Detects shell metacharacter payloads targeting Advantech EKI-1242IEIMS web management interface (CVE-2026-73164, CWE-78)"
        author = "valtersit.com Threat Intelligence"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-73164"
        date = "2026-01-01"
        severity = "high"

    strings:
        $m1 = ";" ascii wide
        $m2 = "|" ascii wide
        $m3 = "&&" ascii wide
        $m4 = "||" ascii wide
        $m5 = "$(" ascii wide
        $m6 = "`" ascii wide

        $cmd1 = "/bin/sh" ascii wide nocase
        $cmd2 = "wget http" ascii wide nocase
        $cmd3 = "curl http" ascii wide nocase
        $cmd4 = "nc -e" ascii wide nocase
        $cmd5 = "chmod +x" ascii wide nocase
        $cmd6 = "rm -rf" ascii wide nocase

    condition:
        uint16(0) == 0x4854 or 2 of ($cmd*) or (2 of ($m*) and 1 of ($cmd*))
}

Note: this rule is intentionally broad and should be scoped to artifacts recovered from the web interface (request logs, PCAP payload extraction, or captured request files), not run against arbitrary file sets.

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-73164 Advantech EKI Web Interface OS Command Injection Attempt"; flow:established,to_server; http.method; content:"GET" or content:"POST"; http.uri; pcre:"/(;|\||&&|\|\||`|\$\().*\b(wget|curl|nc|sh|bash|chmod|rm)\b/i"; reference:cve,2026-73164; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-73164; classtype:web-application-attack; sid:202673164; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=5m
  [network where network.protocol == "http" and
     url.path : ("*cgi-bin*", "*goform*", "*cgi*") and
     url.query : ("*;*", "*|*", "*$(*", "*`*")
   ]
  [process where process.name in ("sh", "bash", "busybox") and
     process.parent.name != null and
     process.args : ("*wget*", "*curl*", "*nc*", "*chmod*")]

The sequence correlates an HTTP request carrying shell metacharacters with immediate shell process execution, which is a strong signal of successful exploitation on hosts where endpoint telemetry from embedded devices is collectable.

Splunk SPL Query

index=web OR index=proxy OR index=ids
(sourcetype=access_combined OR sourcetype=suricata OR sourcetype=pan:traffic)
(uri_path="*cgi-bin*" OR uri_path="*goform*" OR uri_path="*cgi*" OR url="*EKI*")
(uri_query="*;*" OR uri_query="*|*" OR uri_query="*$(*" OR uri_query="*`*"
 OR uri_query="*wget*" OR uri_query="*curl*" OR uri_query="*nc *" OR uri_query="*/bin/sh*")
| eval risk=case(
    match(uri_query,"\$\(|`|;.*\b(wget|curl|nc|sh)\b"), "HIGH",
    match(uri_query,"[;|&]"), "MEDIUM",
    1=1, "LOW")
| stats count min(_time) as first_seen max(_time) as last_seen
        values(uri_path) as paths values(uri_query) as queries
        by src_ip dest_ip risk
| where risk != "LOW"
| sort - count

Wazuh OSSEC Rule

<group name="web,advantech,cve-2026-73164,">
  <rule id="100731" level="12">
    <if_sid>31100</if_sid>
    <id>^40[0-9]$</id>
    <description>CVE-2026-73164: OS command injection attempt against Advantech EKI web interface</description>
    <regex type="pcre2">(?i)(;|\||&&|\|\||`|\$\().{0,40}(wget|curl|nc|/bin/sh|chmod|rm)</regex>
    <group>web_scan,attack,cve_2026_73164,</group>
  </rule>

  <rule id="100732" level="10">
    <if_sid>31100</if_sid>
    <match>cgi-bin</match>
    <regex type="pcre2">(?i)(;|\||&&|`|\$\()</regex>
    <description>CVE-2026-73164: Shell metacharacters in request to EKI management endpoint</description>
    <group>web_scan,attack,</group>
  </rule>
</group>

Adjust rule IDs and if_sid to match the local Wazuh deployment's web-log decoder chain (31100 is the standard Apache/Nginx access-log parent rule).

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No vendor advisory, firmware update, or patch reference was identified by any tracked source at the time of writing. There is no fixed version to recommend.

1. Immediate mitigations (compensating controls, since no patch exists):

   • Isolate the web management interface from untrusted networks. Restrict access via management VLANs, ACLs, or a dedicated out-of-band management network. Never expose the interface to the internet.
   • Enforce strong, unique administrative credentials. Remove or rotate all default accounts. Disable unused accounts and remote-access services on the device.
   • Place the management interface behind a reverse proxy or jump host that performs authentication, session binding, and request inspection, and that rejects requests containing shell metacharacters in parameters.
   • Enable and centrally collect device logs where supported, and monitor for the detection patterns above.
   • Where the device supports it, disable remote web management entirely and administer the device locally or via a hardened, authenticated channel.

2. Patch/upgrade steps:

   • Contact Advantech support directly to request a fixed firmware build and a version matrix; the absence of public patch evidence does not guarantee the vendor has not issued an internal fix. Track the Advantech security advisory page for CVE-2026-73164.
   • Monitor the NVD entry for updates to affected-version and reference fields.
   • Do not deploy unverified third-party firmware. Validate any vendor-provided image by checksum and signature before installation.

3. Long-term hardening:

   • Apply network segmentation consistent with IEC 62443 zones and conduits so that a compromised switch cannot reach critical controllers.
   • Eliminate default credentials at procurement and enforce a credential rotation policy for OT assets.
   • Maintain an inventory of EKI-series firmware versions and include them in vulnerability-management scopes, including agentless or SNMP-based discovery.
   • Require security review of embedded web interfaces during procurement, specifically testing for command-injection classes.
   • Enforce least privilege on the device's own OS where configurable, and require vendors to run management daemons as non-root.

References

1. NVD — CVE-2026-73164: https://nvd.nist.gov/vuln/detail/CVE-2026-73164
2. MITRE CWE-78 — Improper Neutralization of Special Elements used in an OS Command: https://cwe.mitre.org/data/definitions/78.html
3. MITRE ATT&CK T1190 — Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
4. Advantech Security Advisory portal (monitor for an advisory covering EKI-1242IEIMS firmware V1.06.01): https://www.advantech.com/en/support/security
5. Nozomi Networks Labs — credited as the discovering research team in the NVD description; monitor their advisory channel for a technical write-up: https://www.nozominetworks.com/blog

Threat actor and exploit-in-the-wild status: There is no evidence of active exploitation, no CISA KEV listing, no public proof-of-concept, and no named threat-actor campaign associated with CVE-2026-73164 in the data provided. CWE-78 flaws in industrial network devices are historically targeted by both opportunistic actors and OT-focused intrusion sets, so exposure reduction should not wait for exploitation evidence to emerge.