CVE-2026-108918

Executive Summary

CVE-2026-108918 is a critical OS command injection vulnerability in the Edimax BR-6208AC wireless router, firmware version 1.32. An unauthenticated, remotely reachable attacker can manipulate the readE2P argument handled by the /goform/formWlanMP endpoint to execute arbitrary operating system commands on the underlying device. The vendor was contacted but did not respond, the product is end-of-support, and no patch exists — leaving exposed devices fully compromised with a maximum CVSS score of 10.0.

Technical Analysis

The vulnerability resides in the web management component of the Edimax BR-6208AC running firmware 1.32. According to the NVD description, the impacted code is an "unknown function" within the file /goform/formWlanMP, and the flaw is triggered through manipulation of the readE2P argument. The weakness class is CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component, i.e., injection), which in this case manifests as command injection.

Command injection occurs when user-supplied input is concatenated into a shell command or passed to a system-level execution function without adequate sanitization or escaping. The readE2P parameter is intended to control some read operation over an E2P (EEPROM-related) data path within the wireless management (WlanMP) module. Because the application does not neutralize shell metacharacters before using this argument in an operating-system command, an attacker can inject delimiters and additional commands that are executed with the privileges of the web server process — typically root on embedded router firmware.

Key characteristics of this attack surface:

• Pre-authentication reachability: The CVSS vector (AV:N/AC:L/PR:N/UI:N) confirms that no credentials, privileges, or user interaction are required. The /goform/ path family is the standard Edimax configuration interface, and dependent endpoints are frequently reachable without prior authentication on this product line.
• Network exposure: The endpoint is served over HTTP on the router's management interface (LAN side by default, and on some deployments the WAN-facing remote management if enabled). Remote exploitation is explicitly noted as possible.
• Scope change (S:C): The CVSS vector indicates a scope change, meaning the exploited vulnerability in the web application can impact resources beyond its original security authority — consistent with shell-level access escaping the web server context to affect the whole device OS.
• High confidentiality, integrity, and availability impact (C:H/I:H/A:H): Full command execution enables reading of credentials and configuration, modification of firmware/network behavior, and denial of service (e.g., killing critical processes or rebooting).

No further code-level detail (specific function names, exact command construction) is provided in the NVD description. The analysis above is confined to the vulnerability class and the single named endpoint and argument; no additional implementation specifics are asserted.

The vendor did not respond to disclosure contact, and the product is explicitly no longer supported by the maintainer. Consequently, no patched firmware version exists, and no official remediation is available.

Exploitation Scenarios

The following attack chain is inferred from the vulnerability class (OS command injection via the readE2P argument of /goform/formWlanMP) and the data provided. No public PoC code is available in the supplied dataset; the steps below are attack-class level.

1. Reconnaissance / target identification. An attacker scans internet-facing or accessible network ranges for Edimax BR-6208AC management interfaces. Fingerprinting can be done by requesting the /goform/ path family or the device's login page and matching response headers/body to the Edimax web UI. Shodan queries such as http.html:"formWlanMP" or product:"Edimax BR-6208AC" can identify candidate hosts.

2. Triggering the flaw. The attacker sends an HTTP request to /goform/formWlanMP with the readE2P argument set to a value containing shell metacharacters (for example, command separators or substitution sequences). Because the application passes this argument into a system command without neutralization, the injected characters break out of the intended argument context.

3. Payload / execution (class level). The injected content causes the underlying shell to execute an attacker-chosen command in addition to, or instead of, the intended E2P read operation. The command runs with the privileges of the web service (commonly root on embedded router platforms). Typical objectives at this stage are execution of a downloaded script or establishing a reverse shell to an attacker-controlled host. No specific payload strings or filenames are provided by the source data and none are asserted here.

4. Post-exploitation impact. With command execution, the attacker can:

   • Extract stored credentials, Wi-Fi keys, and device configuration.
   • Modify DNS settings, routing, or firewall rules to redirect or intercept traffic.
   • Enroll the device into a botnet (common for SOHO routers) or use it as a pivot into the LAN.
   • Disable logging or security services, and persist across reboots via startup scripts.

The attack is fully remote and requires no authentication. The public availability of exploit details ("The exploit is publicly available and might be used") raises the likelihood of opportunistic mass exploitation, even without a weaponized PoC in this dataset.

Impact Assessment

CVE-2026-108918 carries a CVSS v3.1 base score of 10.0 — the maximum — with the vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

• Attack Vector: Network — exploitable remotely across a network path, not requiring local access.
• Attack Complexity: Low — no special conditions, race windows, or advanced knowledge; a single crafted request suffices.
• Privileges Required: None — no authentication needed.
• User Interaction: None — the victim does not need to click or approve anything.
• Scope: Changed — the impact extends beyond the web application to the device operating system and potentially the surrounding network.
• Confidentiality/Integrity/Availability: High — full command execution yields complete loss of confidentiality (config, keys, credentials), integrity (firmware, routing, DNS), and availability (DoS, bricking, reboots).

Blast radius: Any Edimax BR-6208AC running firmware 1.32 that exposes the web management interface is at risk. Because the product is end-of-support, all deployments remain permanently vulnerable. If the management interface is reachable from the WAN (remote management enabled) or the device sits on an untrusted LAN segment (guest networks, shared offices, retail), the exposure is severe. Compromised routers are high-value footholds: they see all passing traffic and can be used to pivot deeper into the network. Consumer/SOHO deployments, small offices, and any environment relying on this legacy router inherit the full 10.0 risk with no vendor remedy.

EPSS has not yet been scored by FIRST.org; no probability estimate is asserted.

Detection Guidance

Sigma Rule

title: Edimax BR-6208AC Command Injection via readE2P (CVE-2026-108918)
id: 7b2c1f4e-9a3d-4c8e-b1f6-2d5e6a7c8b90
status: experimental
description: Detects HTTP requests to /goform/formWlanMP containing shell metacharacters in the readE2P argument, indicative of command injection against Edimax BR-6208AC firmware 1.32.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-108918
author: valtersit.com
date: 2026-01-01
logsource:
  category: webserver
  product: edimax
detection:
  selection_uri:
    cs-uri-stem|contains: '/goform/formWlanMP'
  selection_param:
    cs-uri-query|contains:
      - 'readE2P='
  selection_metachar:
    cs-uri-query|contains:
      - ';'
      - '|'
      - '&&'
      - '`'
      - '$('
      - '%3B'
      - '%7C'
      - '%26%26'
      - '%60'
  condition: selection_uri and selection_param and selection_metachar
fields:
  - c-ip
  - cs-uri-stem
  - cs-uri-query
falsepositives:
  - Legitimate administration tooling that passes encoded data containing separator characters
level: critical
tags:
  - attack.t1190
  - cve.2026-108918

YARA Rule

rule CVE_2026_108918_Edimax_FormWlanMP_Exploit
{
    meta:
        description = "Detects HTTP requests exploiting command injection in Edimax BR-6208AC /goform/formWlanMP via readE2P (CVE-2026-108918)"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-108918"
        date = "2026-01-01"
        severity = "critical"

    strings:
        $uri = "/goform/formWlanMP" ascii nocase
        $param = "readE2P" ascii nocase
        $meta1 = ";" ascii
        $meta2 = "|" ascii
        $meta3 = "&&" ascii
        $meta4 = "`" ascii
        $meta5 = "$(" ascii

    condition:
        $uri and $param and any of ($meta*)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-108918 Edimax BR-6208AC Command Injection via readE2P"; flow:to_server,established; http.uri; content:"/goform/formWlanMP"; http.uri; content:"readE2P"; pcre:"/readE2P=[^&\\n]*(;|\\||&&|`|\\$\\()/Ui"; classtype:attempted-admin; reference:cve,2026-108918; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-108918; metadata:created_at 2026_01_01, updated_at 2026_01_01; sid:2026108918; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=10s
  [ network where network.protocol == "http" and url.path == "/goform/formWlanMP" and url.query : "readE2P" ]
  [ network where network.protocol == "http" and url.path == "/goform/formWlanMP" and url.query regex~ ".*(;|\\||&&|`|\\$\\()(.)*" ]

Splunk SPL Query

index=web OR index=proxy
| eval uri = coalesce(url, cs_uri_stem, uri_path)
| eval qry = coalesce(url_query, cs_uri_query, query_string)
| where like(uri, "%/goform/formWlanMP%") AND like(qry, "%readE2P%")
| where match(qry, "(;|\||&&|`|\$\()")
| stats count min(_time) as first_seen max(_time) as last_seen latest(src_ip) as src_ip values(qry) as queries by dest_ip
| convert ctime(first_seen) ctime(last_seen)
| sort - count

Wazuh OSSEC Rule

<group name="web,edimax,cve-2026-108918,">
  <rule id="2026108918" level="15">
    <decoded_as>web-accesslog</decoded_as>
    <field name="url">\/goform\/formWlanMP</field>
    <field name="url">readE2P</field>
    <regex type="pcre2">readE2P=[^&\s]*(;|\||&&|`|\$)\(?)</regex>
    <description>CVE-2026-108918: Edimax BR-6208AC command injection attempt against /goform/formWlanMP (readE2P)</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>attack,,attempted_admin,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). No vendor fix, firmware update, or workaround is available. The vendor did not respond to disclosure, and the product is end-of-support.

1. Immediate mitigations

   • Retire or replace the device. Because the product is end-of-support and no patch will be issued, the only fully effective remediation is to decommission the Edimax BR-6208AC and replace it with a vendor-supported router.
   • Remove WAN exposure. Disable remote management so the /goform/ interface is not reachable from the internet. Confirm with an external port scan.
   • Segment and restrict access. Place the device behind a firewall and restrict management access to a dedicated, trusted VLAN. Block inbound access to the router's HTTP management port from untrusted segments.
   • Disable the management interface entirely where operationally possible (e.g., operate as a pure access point/bridge if the device allows).

2. Patch / upgrade steps

   • No firmware patch exists. Do not wait for one; plan hardware replacement.
   • Monitor the Edimax support site and NVD entry for any late advisory; however, given end-of-support status and lack of vendor response, treat remediation-by-patch as unavailable.

3. Long-term hardening

   • Maintain a hardware/firmware lifecycle inventory and proactively replace devices that reach end-of-support.
   • Enforce HTTPS-only management with strong credentials; never expose router admin UIs to the WAN.
   • Apply egress/ingress filtering and network monitoring to detect injected commands and reverse-shell callbacks from embedded devices.
   • Adopt a vulnerability management process that flags end-of-life network equipment as high priority regardless of individual CVE scores.

References

• NVD — CVE-2026-108918: https://nvd.nist.gov/vuln/detail/CVE-2026-108918
• CWE-74 — Improper Neutralization of Special Elements in Output Used by a Downstream Component: https://cwe.mitre.org/data/definitions/74.html
• MITRE ATT&CK T1190 — Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
• Edimax BR-6208AC product/support page (vendor): https://www.edimax.com/
• FIRST EPSS (score pending): https://www.first.org/epss/

No CISA KEV listing exists for this CVE, and no named threat actor campaign or confirmed in-the-wild exploitation is documented in the provided data. The NVD notes that the exploit is publicly available and "might be used."