CVE-2026-101073

Executive Summary

CVE-2026-101073 is an improper authentication vulnerability (CWE-287) affecting the Netcore NR289-GE router firmware version 1.4.5102. The flaw resides in the /bin/boa binary — specifically within the CGI Dispatcher component — and can be triggered remotely by an unauthenticated attacker. Given the CVSS score of 8.3 (High) with network reachability, no privileges required, no user interaction, and a scope change, exploitation could allow unauthorized access to the device's management interface, leading to configuration changes, traffic interception, or use of the device as a pivot point within the network. The vendor was contacted early but did not respond, and no official patch is currently available.

Technical Analysis

The vulnerability is classified as CWE-287: Improper Authentication, meaning the software does not adequately verify that a request originates from an authenticated or authorized source. In this case, the affected component is the Boa web server (/bin/boa) acting as a CGI Dispatcher. The Boa web server is a lightweight, open-source HTTP server commonly used in embedded Linux devices such as routers and IoT gateways. Its CGI dispatcher processes HTTP requests and invokes handler routines based on the requested path.

The NVD description states that an "unknown function" of /bin/boa is impacted and that "performing a manipulation results in improper authentication." This indicates that a crafted HTTP request — likely malformed or targeted at a specific URI — causes the CGI dispatcher to bypass or incorrectly perform an authentication check. Importantly, no specific function names, parameter names, or code snippets are provided in the authoritative description. Therefore, the exact technical trigger (e.g., a missing session validation on a particular endpoint, a path traversal in the dispatcher, or a request smuggling technique) cannot be confirmed from the available data.

What is known:

• The attack vector is network-based (AV:N) and requires no privileges (PR:N) and no user interaction (UI:N).
• The CVSS vector indicates a scope change (S:C), meaning exploitation could affect resources beyond the vulnerable component itself — for example, the underlying operating system, other processes, or adjacent network segments.
• The impact to confidentiality, integrity, and availability is rated Low (C:L/I:L/A:L), suggesting limited but tangible damage — likely unauthorized access to configuration data, minor modifications, or temporary service disruption.

The fact that the vulnerability exists in the CGI Dispatcher suggests that the authentication logic may be handled inconsistently across different CGI endpoints, or that a specific request path bypasses the normal session check entirely. Without vendor confirmation or a technical write‑up, the precise mechanism remains inferred.

Exploitation Scenarios

Note: No public PoC or exploit code is available. The following scenario is inferred from the vulnerability class (CWE-287) and the NVD description.

1. Reconnaissance / Target Identification An attacker scans the internet or a local network for devices running the Netcore NR289-GE firmware. This can be done using Shodan searches for HTTP titles or HTML keywords associated with the device. Because the Boa web server typically listens on port 80 or 443, the attacker identifies live hosts by probing for the login page or a known CGI path.

2. Triggering the Improper Authentication The attacker sends a specially crafted HTTP request to the Boa web server. Based on the vulnerability class, this request likely targets a CGI endpoint that is supposed to require authentication but fails to enforce it correctly. For example, the dispatcher may process a request without verifying a session cookie, or it may treat a specific HTTP method (e.g., POST, PUT) or header in a way that bypasses the authentication check. The exact request structure is not publicly documented; however, the phrase "performing a manipulation results in improper authentication" suggests that the attacker manipulates a request parameter or path to reach a privileged function.

Because no user interaction is required and the attack is remote, the attacker can automate this step at scale.

3. Execution / Access If the improper authentication is successful, the attacker gains access to protected resources — potentially the administrative web interface or CGI scripts that allow configuration changes. At this stage, the attacker may be able to:

• Read or modify device configuration (e.g., Wi‑Fi credentials, port forwarding rules, DNS settings).
• Upload malicious firmware or execute system commands if the CGI handler permits it.
• Use the device as a foothold to attack other systems on the internal network (due to scope change).

4. Post‑Exploitation Impact With unauthorized access, the attacker could redirect traffic, intercept sensitive data, or add the device to a botnet. The scope change (S:C) indicates that the compromise could extend beyond the router itself, affecting connected clients or upstream network segments. The low integrity and availability impact suggests the attacker may not be able to fully brick the device, but can still cause significant operational disruption.

Impact Assessment

The CVSS v3.1 base score of 8.3 (High) reflects a serious vulnerability that is remotely exploitable without authentication. The vector breaks down as follows:

• AV:N — Attackable over the network (internet or LAN).
• AC:L — Low attack complexity; no specialized conditions required.
• PR:N — No privileges needed; an unauthenticated attacker can exploit.
• UI:N — No user interaction; the victim does not need to click anything.
• S:C — Scope change; the impact may affect resources beyond the vulnerable component (e.g., the OS or other network devices).
• C:L / I:L / A:L — Low confidentiality, integrity, and availability impact.

Business Impact:

• Network compromise: An attacker can gain control of the router, potentially intercepting or redirecting all traffic passing through it.
• Lateral movement: The device can be used as a pivot point to reach internal systems that are otherwise not exposed to the internet.
• Data breach: Configuration data, credentials, and possibly traffic payloads could be exfiltrated.
• Operational disruption: Changes to routing, DNS, or firewall rules can cause outages or man‑in‑the‑middle attacks.

Affected Systems: All Netcore NR289-GE devices running firmware version 1.4.5102. The exact number of exposed devices is unknown, but similar routers are often deployed in small offices, retail locations, and homes. Internet‑facing instances are at highest risk.

Blast Radius: Because of the scope change, a single compromised router could affect every device behind it. In an enterprise context, this could mean a branch office gateway being used to infiltrate the corporate network.

Detection Guidance

Sigma Rule

title: Netcore NR289-GE Improper Authentication Attempt
id: 7a9c2e1f-4b3d-4a5c-9e8f-1a2b3c4d5e6f
status: experimental
description: Detects HTTP requests targeting the Boa CGI dispatcher on Netcore NR289-GE devices that may indicate exploitation of CVE-2026-101073.
author: Threat Intelligence Team
date: 2026-01-15
logsource:
  category: webserver
  product: boa
detection:
  selection:
    cs-uri-stem|contains:
      - '/cgi-bin/'
      - '/boafrm/'
    sc-status: 200
  condition: selection
falsepositives:
  - Legitimate administrative activity
level: high
tags:
  - attack.initial_access
  - attack.t1190
  - cve.2026.101073

YARA Rule

rule CVE_2026_101073_Netcore_Boa_Improper_Auth
{
    meta:
        description = "Detects potential exploitation of CVE-2026-101073 in Netcore NR289-GE firmware"
        author = "Threat Intelligence Team"
        date = "2026-01-15"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-101073"
        hash = "unknown"
    strings:
        $boa = "/bin/boa"
        $cgi = "CGI Dispatcher"
        $netcore = "Netcore"
        $nr289 = "NR289-GE"
    condition:
        any of them
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-101073 Netcore NR289-GE Improper Authentication Attempt"; flow:to_server,established; content:"/cgi-bin/"; http_uri; content:"Netcore"; http_header; sid:10000001; rev:1; reference:cve,2026-101073; classtype:attempted-admin;)

Elastic Detection

sequence by host.id with maxspan=5s
  [ network where network.protocol == "http" and
    http.request.method == "POST" and
    url.path : "/cgi-bin/*" and
    http.response.status_code == 200 ]

Splunk SPL Query

index=web sourcetype=access_common
| search (uri_path="/cgi-bin/*" OR uri_path="/boafrm/*")
| where status=200 AND (useragent="*" OR referer="*")
| stats count by src_ip, uri_path, status
| where count > 5
| sort - count

Wazuh OSSEC Rule

<group name="netcore,boa,">
  <rule id="100100" level="10">
    <decoded_as>web-accesslog</decoded_as>
    <url>/cgi-bin/</url>
    <status>200</status>
    <description>CVE-2026-101073: Possible improper authentication exploitation on Netcore NR289-GE Boa web server</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>cve_2026_101073,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No patch evidence from any tracked source. The vendor (Netcore) was contacted early but did not respond, and no official firmware update is available.

1. Immediate Mitigations:

• Restrict network access: Disable remote management (WAN access) on the router if not strictly required. If remote management is needed, restrict it to specific trusted IP addresses via firewall rules.
• Segment the network: Place the router in a separate VLAN or network segment with strict access controls to limit lateral movement.
• Monitor for exploitation: Use the detection rules provided above to identify suspicious requests to the Boa web server.
• Disable unnecessary services: Turn off any CGI functionality that is not essential for device operation.

2. Patch/Upgrade Steps:

• No vendor patch is available. Check the Netcore support website periodically for firmware updates. If a patch is released, apply it immediately after validating the hash and testing in a non‑production environment.
• As an interim workaround, consider replacing the device with a supported model from a different vendor if criticality is high.

3. Long‑Term Hardening:

• Implement a vulnerability management program that includes regular scanning for embedded devices.
• Enforce strong authentication and session management on all network devices; avoid default credentials.
• Use network monitoring to baseline normal traffic to and from routers and alert on anomalous CGI requests.
• Consider a zero‑trust architecture where device management is isolated from general network traffic.

References

1. NVD — CVE-2026-101073: https://nvd.nist.gov/vuln/detail/CVE-2026-101073
2. CWE-287: Improper Authentication — https://cwe.mitre.org/data/definitions/287.html
3. MITRE ATT&CK T1190: Exploit Public-Facing Application — https://attack.mitre.org/techniques/T1190/
4. Vendor Netcore support portal (no advisory available at time of writing)
5. CISA KEV Catalog — CVE not listed as of 2026-01-15