CVE-2026-108932

Executive Summary

CVE-2026-108932 is a reflected cross-site scripting (XSS) vulnerability in Netcore NR268 firmware version 1.7.121109, specifically affecting the DHCP Hostname Handler component reachable through filter_hosts_dump.cgi. An attacker who can influence the Hostname argument can inject client-side script that executes in the browser context of a victim who views the crafted request, and the exploit has been publicly disclosed. The vulnerability is remotely triggerable over the network but requires user interaction, resulting in a CVSS v3.1 base score of 4.3. Because no patch or vendor response exists, exposed NR268 devices remain at risk until compensating controls are applied.

Technical Analysis

The affected product is the Netcore NR268 router/firmware release 1.7.121109. According to the NVD description, the flaw resides in the filter_hosts_dump.cgi script/component, within the DHCP Hostname Handler logic. The description explicitly states that the vulnerable behavior "impacts the function eval" and that the injection point is the Hostname argument. The manipulation of this argument results in cross-site scripting (CWE-79).

Mechanically, this is a reflected XSS class vulnerability: user-supplied input provided via the Hostname parameter is not adequately sanitized or output-encoded before being written into a response generated by filter_hosts_dump.cgi. The NVD text indicates that the value reaches an eval construct, which is the sink that turns the unsanitized Hostname value into script execution within the page context. The DHCP Hostname Handler is the component context — DHCP hostname data is the input surface that flows into this handler and subsequently into the vulnerable dump path.

Two conditions are required for successful exploitation per the CVSS vector (UI:R, meaning User Interaction is Required): the target must be reachable over the network (AV:N), and the victim must take an action — for example, following a crafted link or loading a page with the injected parameter — for the script to execute in their browser session. No privileges are required (PR:N), and the scope is unchanged (S:U). Confidentiality impact is None (C:N), Integrity impact is Low (I:L), and Availability impact is None (A:N) per the assigned vector.

The reason confidentiality is rated None and integrity only Low is that the injected script executes in the victim's browser session against the device's own web interface; the practical ceiling of this vulnerability class (session cookie theft, CSRF-style state change, or UI redressing) is bounded by the trust relationship between the victim's browser and the NR268 management interface. The report does not assert any confirmed data-exfiltration impact beyond what the vector supports.

It is important to be precise about what is and is not known. The description confirms: the file filter_hosts_dump.cgi, the component "DHCP Hostname Handler," the argument Hostname, the eval sink, and the XSS classification. It does not provide the exact request method, header names, or full parameter serialization beyond the Hostname argument, so those specifics are not asserted here. What can be said is that any code path that pipes DHCP-derived hostname strings into an evaluated output within this CGI is inherently dangerous, because DHCP hostname fields are attacker-influenceable on networks where the device leases addresses to or accepts hostname metadata from untrusted endpoints.

Exploitation Scenarios

No public proof-of-concept code, Nuclei template, or exploit-database entry is available for CVE-2026-108932. The attack chain below is inferred at the vulnerability-class level (reflected XSS via an unsanitized parameter), consistent with the NVD description and CVSS vector. No specific implementation details beyond those named in the description (filter_hosts_dump.cgi, Hostname argument, eval function, DHCP Hostname Handler component) are invented.

1. Reconnaissance / target identification. The attacker identifies an internet- or LAN-exposed Netcore NR268 management interface running firmware 1.7.121109. This can be done through banner/response fingerprinting (for example by querying Shodan for product:"Netcore NR268" or search-engine scraping) or by direct probing of the filter_hosts_dump.cgi endpoint on a candidate host. The attacker confirms the firmware version where possible and locates the CGI path.

2. Triggering the flaw class (reflected XSS). The attacker crafts a request to filter_hosts_dump.cgi in which the Hostname argument contains a script payload instead of a legitimate DHCP hostname string. Because the handler fails to sanitize/encode the value before delivering it into the evaluated output, the attacker's markup is reflected into the response page.

3. Delivery / execution method. Delivery is via a crafted URL or link sent to a victim (phishing email, chat message, or a link placed on a page the victim visits). The victim must interact with the link while authenticated to (or able to reach) the NR268 web interface. When the browser loads the crafted request, the injected script executes in the context of the management interface's origin. This is the mechanism the CVSS UI:R component encodes: the attacker needs the victim's browser to make the request.

4. Post-exploitation impact. Executing script in the device's origin allows the attacker to read or act within that page context — for example, performing actions the victim's session is authorized to perform or exfiltrating data readable from the DOM — bounded by the integrity-only/low-impact scoring in the official CVSS vector. The public disclosure means attackers already have the conceptual blueprint and, per the NVD text, "may be utilizing" it, so targeted social-engineering campaigns against NR268 operators are a realistic near-term risk.

Impact Assessment

The business impact center is on operators of Netcore NR268 devices: small-to-medium network deployments, branch offices, and home/soho environments where these devices serve DHCP and are administered through the embedded web UI. The CVSS v3.1 base score of 4.3 (Medium) reflects a network-reachable flaw (AV:N), no privileges required (PR:N), and no special attack complexity (AC:L), but constrained by mandatory user interaction (UI:R) and low/neutral direct-impact subscores — Confidentiality None, Integrity Low, Availability None, Scope Unchanged.

Blast radius is constrained in the sense that successful exploitation affects the victim's browser session touching the device's web origin, not the device's control plane or the confidentiality of arbitrary stored data. However, because the router is often the management nexus for a whole network segment, a compromised admin session can translate into configuration changes (integrity impact) — this is the practical multiplier. The lack of a vendor patch elevates the residual risk: every NR268 running 1.7.121109 that exposes this CGI remains vulnerable until compensating controls are in place.

A critical operational point: the NVD description states the vendor was contacted early and did not respond. That means no official fixed firmware version, advisory, or CVE-to-patch mapping exists. Organizations should treat any exposure of this endpoint to untrusted networks as an unmitigated risk and prioritize network-level isolation.

Detection Guidance

Sigma Rule

title: Netcore NR268 filter_hosts_dump.cgi Hostname XSS Attempt
id: 4c1e9b7a-2f6d-4b8e-9a1c-7d3e5f0a9b21
status: experimental
description: Detects HTTP requests to filter_hosts_dump.cgi containing script-like payloads in the Hostname parameter, targeting CVE-2026-108932 (reflected XSS).
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-108932
author: valtersit threat intel
date: 2026/01/01
logsource:
  category: webserver
detection:
  selection_uri:
    cs-uri-stem|endswith: 'filter_hosts_dump.cgi'
  selection_payload:
    cs-uri-query|contains:
      - 'Hostname='
  selection_patterns:
    cs-uri-query|contains:
      - '<script'
      - '%3Cscript'
      - 'javascript:'
      - 'onerror='
      - 'onload='
      - 'document.cookie'
  condition: selection_uri and selection_payload and selection_patterns
fields:
  - c-ip
  - cs-uri-stem
  - cs-uri-query
  - cs User-Agent
falsepositives:
  - Legitimate hostname values that coincidentally contain script-like substrings (rare)
level: medium
tags:
  - attack.t1189
  - cve.2026.108932

YARA Rule

rule CVE_2026_108932_Netcore_NR268_XSS
{
    meta:
        description = "Detects script-injection attempts targeting Netcore NR268 filter_hosts_dump.cgi Hostname parameter (CVE-2026-108932)"
        author = "valtersit threat intel"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-108932"
        date = "2026-01-01"
        severity = "medium"

    strings:
        $cgi = "filter_hosts_dump.cgi" ascii nocase
        $param = "Hostname=" ascii nocase
        $s1 = "<script" ascii nocase
        $s2 = "%3Cscript" ascii nocase
        $s3 = "javascript:" ascii nocase
        $s4 = "onerror=" ascii nocase
        $s5 = "document.cookie" ascii nocase

    condition:
        $cgi and $param and any of ($s*)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-108932 Netcore NR268 filter_hosts_dump.cgi Hostname XSS attempt"; flow:established,to_server; http.uri; content:"filter_hosts_dump.cgi"; nocase; http.uri; content:"Hostname="; nocase; pcre:"/(%3C|<)script|javascript%3A|onerror%3D|onload%3D/i"; classtype:web-application-attack; reference:cve,2026-108932; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-108932; sid:2026108932; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=1m
  [network where network.protocol == "http" and url.path : "*filter_hosts_dump.cgi" and url.query : "*Hostname=*"]
  [network where network.protocol == "http" and url.query : ("*<script*" or "*%3Cscript*" or "*javascript:*" or "*onerror=*" or "*document.cookie*")]

Splunk SPL Query

index=web OR index=proxy sourcetype=access_combined OR sourcetype=stream:http
| search uri_path="*filter_hosts_dump.cgi*" OR url="*filter_hosts_dump.cgi*"
| search (uri_query="*Hostname=*" OR url="*Hostname=*")
| search (uri_query="*<script*" OR uri_query="*%3Cscript*" OR uri_query="*javascript:*" OR uri_query="*onerror=*" OR uri_query="*onload=*" OR url="*<script*" OR url="*%3Cscript*")
| stats count min(_time) as first_seen max(_time) as last_seen by src_ip, dest_host, uri_path, uri_query
| sort - count

Wazuh OSSEC Rule

<group name="web,appsec,cve-2026-108932,">
  <rule id="2026108" level="10">
    <decoded_as>web-accesslog</decoded_as>
    <url>filter_hosts_dump.cgi</url>
    <regex type="pcre2">Hostname=.*(%3C|<)script|javascript%3A|onerror%3D|onload%3D</regex>
    <description>CVE-2026-108932: Possible reflected XSS attempt against Netcore NR268 filter_hosts_dump.cgi Hostname parameter</description>
    <mitre>
      <id>T1189</id>
    </mitre>
    <group>web_attack,xss,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). No vendor fix, fixed version, or workaround was published or provided; the vendor did not respond to the disclosure.

1. Immediate mitigations.

• Network isolation: never expose the Netcore NR268 management interface or the filter_hosts_dump.cgi endpoint to untrusted networks or the public internet. Restrict management-plane access to a dedicated, trusted VLAN via firewall rules.
• Access control: place the web UI behind an authenticating reverse proxy or VPN, and where supported, restrict source IPs that may reach .cgi endpoints.
• Input filtering at the edge: deploy a WAF or proxy rule (see detection content above) that rejects requests to filter_hosts_dump.cgi containing script-like content in the Hostname argument. This is a compensating control, not a fix.
• User awareness: since exploitation requires user interaction, brief administrators on phishing links that point at device-management URLs.

2. Patch/upgrade steps.

• There is no vendor patch. Monitor the vendor and the NVD entry (https://nvd.nist.gov/vuln/detail/CVE-2026-108932) for any fixed firmware release. If Netcore publishes a firmware update, treat it as the remediation path and validate the version change on the device.
• If no patch materializes, evaluate device replacement or operational retirement of the NR268 1.7.121109 in exposed deployments.

3. Long-term hardening.

• Apply a repeatable patch-management process for embedded network gear, and inventory firmware versions so affected 1.7.121109 units are identifiable.
• Enforce output-encoding and input-validation standards for CGI/web components when firmware is developed or procured; treat DHCP-supplied hostname fields as untrusted input.
• Disable unused CGI endpoints and services on the device where configuration permits.
• Maintain network segmentation so a compromised admin session on one device does not expose the broader management plane.

References

• NVD — CVE-2026-108932: https://nvd.nist.gov/vuln/detail/CVE-2026-108932
• MITRE ATT&CK — T1189 Drive-by Compromise: https://attack.mitre.org/techniques/T1189/
• CWE-79 — Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'): https://cwe.mitre.org/data/definitions/79.html
• FIRST EPSS — not yet scored at time of writing: https://www.first.org/epss/
• CISA Known Exploited Vulnerabilities Catalog — CVE-2026-108932 not listed (no KEV entry as of this report): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Threat actor / exploit-in-the-wild note: No named threat-actor campaign is attributable to CVE-2026-108932 based on open data. The NVD description states the exploit has been publicly disclosed and "may be utilized"; no exploit code, Nuclei template, or Metasploit module is currently available, so any in-the-wild activity is presumptive rather than confirmed.