CVE-2026-82703

Executive Summary

CVE-2026-82703 is an unauthenticated-to-partially-authenticated OS command injection vulnerability in the Edimax BR-6214K router, specifically within firmware version 1.40. The flaw resides in the system function called by the www/ping.asp file, within the asp_setPing endpoint, where the pingstr argument is improperly sanitized before being passed to underlying OS command execution. An attacker who can reach the affected management interface can inject arbitrary operating system commands, potentially achieving remote code execution on the device. The vulnerability has a CVSS score of 6.6 (HIGH), with a public exploit released, and the vendor has not responded to disclosure attempts, leaving the affected device without a patch.

Technical Analysis

The vulnerability is a classic OS command injection flaw (CWE-77) identified in the Edimax BR-6214K router firmware version 1.40. The affected code path resides in the system function invoked by the web-based management interface, specifically within the www/ping.asp file handling the asp_setPing endpoint. The pingstr argument is processed by the vulnerable endpoint. When the application constructs an OS command containing the user-controlled pingstr value, it fails to sanitize or validate the input before executing it via the system call.

The attack surface is the web management interface of the router, which is typically exposed on TCP port 80 (HTTP) and occasionally port 443 (HTTPS) when remote management is enabled. The asp_setPing endpoint is part of the ping diagnostic utility commonly found in consumer/SOHO router web interfaces. The endpoint accepts the pingstr parameter, which is intended to hold an IP address or hostname for the ping diagnostic — but can instead carry shell metacharacters such as ;, &&, |, $(), or backticks.

The criticality of this vulnerability is elevated by several factors: (a) the attack can be initiated remotely (AV:N in CVSS), meaning an attacker does not need physical access; (b) the attack has low complexity (AC:L) requiring no special conditions; (c) it impacts confidentiality, integrity, and availability (C:L/I:L/A:L); and (d) it has a scope change (S:C) indicating the compromised component can impact resources beyond the vulnerable component's security scope. An exploit has been publicly released, significantly increasing the practical risk to deployed devices. The vendor has not responded to coordinated disclosure, suggesting no patch will be forthcoming.

Exploitation Scenarios

1. Reconnaissance/Target Identification: An attacker begins by scanning internet-facing address space for devices responding to HTTP requests that present the Edimax BR-6214K administrative web interface. Shodan and other internet-wide scanners can identify these devices by their default page titles or specific HTTP headers. Given that the device is a router, targets are also discoverable through routers' default gateway behavior.

2. Triggering the Flaw: The attacker navigates to the management interface and accesses the www/ping.asp page, which hosts the asp_setPing endpoint. The pingstr parameter in the request is the injection point. The attacker submits a crafted HTTP GET or POST request to the endpoint containing a benign ping target concatenated with shell metacharacters and injected commands, e.g., pingstr=8.8.8.8;id (illustrative example — actual payload syntax depends on the underlying command construction).

3. Payload/Execution Method: Because the application passes the unsanitized pingstr value to the system function, the crafted string is executed by the device's underlying Linux/Unix shell. The injected payload executes with the privileges of the web server process, typically root on embedded router firmware. Payloads can include command chaining operators, redirection to write files, or initiating reverse shell connections. No public PoC is available; the attack chain is inferred from the vulnerability class described in the NVD entry.

4. Post-Exploitation Impact: Successful command injection grants the attacker arbitrary command execution on the router. With this access, the attacker can: modify firewall rules to allow further network access, intercept or reroute LAN traffic, exfiltrate credentials stored in configuration files, install persistent malware/backdoors, enroll the device in botnets, or use the router as a pivot point to attack internal network hosts. The CVSS scope change (S:C) confirms that the impact extends beyond the router itself, potentially affecting the entire connected network.

Impact Assessment

Business Impact: For enterprise environments that may use the BR-6214K in branch offices or remote sites, an attacker with control of the router can effectively monitor, intercept, and manipulate all traffic flowing through the device. This compromises the confidentiality of sensitive business communications and the integrity of data in transit.

Affected Systems and Blast Radius: All Edimax BR-6214K routers running firmware version 1.40 are affected. The blast radius extends to the entire LAN segment behind the router, as well as any VPN-terminated or DMZ-hosted assets that route through the device. An attacker controlling the router becomes a "man-in-the-middle" for all traffic, enabling credential harvesting, data exfiltration, and lateral movement.

CVSS Subscores Analysis: The CVSS vector (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L) reveals an important nuance: although remote and low-complexity, the attack requires High privileges (PR:H). This indicates that an attacker must already have authenticated access to the management interface, or have captured/guessed default credentials (Edimax devices are commonly deployed with default credentials such as "admin/admin" — a common default credential pattern for this device class, though not individually confirmed for this model). The scope change (S:C) combined with moderate CIA impact (L/L/L) results in the overall score of 6.6, rating this a HIGH severity issue. The low CIA intensities reflect the limited direct impact of the initial compromise, but the high privilege requirement and scope change collectively make this a significant security concern.

Detection Guidance

Sigma Rule

title: Edimax BR-6214K asp_setPing OS Command Injection Attempt
id: 8f4623a8-e581-4b6c-9a3c-d72d5d9f5123
status: experimental
description: Detects OS command injection attempts targeting the asp_setPing endpoint on Edimax BR-6214K routers
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-82703
author: Valters IT Security
date: 2026/01/15
logsource:
    category: webserver
    product: apache
    definition: 'Web server logs from Edimax router management interface'
detection:
    selection:
        cs-uri-query|contains|all:
            - 'pingstr='
            - ';'
        cs-uri-query|contains:
            - 'etc/passwd'
            - 'cmd'
            - 'wget'
            - 'curl'
            - 'nc '
            - 'telnet'
            - 'sh -c'
            - 'busybox'
            - 'cd /tmp'
    condition: selection
falsepositives:
    - Legitimate ping tests using semicolons are unlikely but possible
level: high
tags:
    - attack.persistence
    - attack.t1190
    - cve.2026-82703

YARA Rule

rule CVE_2026_82703_Edimax_asp_setPing_Injection
{
    meta:
        author = "Valters IT Security"
        description = "Detects network traffic patterns associated with OS command injection against Edimax BR-6214K pingstr endpoint"
        date = "2026-01-15"
        cve = "CVE-2026-82703"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-82703"
    strings:
        $endpoint = "pingstr=" ascii wide nocase
        $ping_path = "ping.asp" ascii wide nocase
        $cmd_chain1 = ";%20" ascii wide
        $cmd_chain2 = ";id" ascii wide nocase
        $cmd_chain3 = ";cat%20/etc/passwd" ascii wide nocase
        $cmd_chain4 = && ascii wide
        $cmd_chain5 = "|%20" ascii wide
        $cmd_chain6 = "wget" ascii wide nocase
        $cmd_chain7 = "usb/" ascii wide nocase
    condition:
        uint16(0) == 0x0d0a or
        any of ($endpoint, $ping_path) and (
            1 of ($cmd_chain*) or
            any of them
        ) and filesize < 100KB
}

Suricata IDS Rule

alert http any any -> $HOME_NET any (msg:"CVE-2026-82703 Edimax BR-6214K asp_setPing OS Command Injection Attempt"; flow:established,to_server; http.uri; content:"ping.asp"; http.uri; content:"pingstr="; pcre:"/pingstr=.+(?:;|\x26\x26|\||\$\(|`)[a-z]+/i"; classtype:attempted-admin; reference:cve,2026-82703; reference:url,https://nvd.nist.gov/vuln/detail/CVE-2026-82703; sid:1000827; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=5m
  [network where event.category == "http" and 
     http.request.method == "GET" or http.request.method == "POST" and
     url.path contains "ping.asp" and
     url.query contains "pingstr="]
  [network where event.category == "http" and 
     url.query matches ".*(;|&&|\\||\\$\\(|`).*(id|wget|curl|busybox|cat|sh).*" or
     url.query matches ".*(;|&&|\\||\\$\\(|`).*\\s[A-Za-z]{2,}.*"]

Splunk SPL Query

index=web sourcetype=access_combined uri_path="*ping.asp*" 
| rex field=uri_query "pingstr=(?<pingstr>[^&]+)"
| where match(pingstr, "(;|&&|\||\$\w+|`|>\s*/)")
| stats count min(_time) max(_time) by src_ip uri_query status
| where count > 3
| sort -count

Wazuh OSSEC Rule

<group name="edimax,cve-2026-82703">
  <rule id="100827" level="12">
    <decoded_as>web-access</decoded_as>
    <field name="url" type="pcre2">ping\.asp.*pingstr=.*(;|\&\&|\||\$\w+|`)</field>
    <description>Edimax BR-6214K asp_setPing OS command injection attempt (CVE-2026-82703)</description>
    <group>attack_exploitation,attacker_attempted_os_command_injection,t1190,</group>
    <mitre>
      <id>T1190</id>
    </mitre>
    <info type="link">https://nvd.nist.gov/vuln/detail/CVE-2026-82703</info>
  </rule>
</group>

Mitigation & Patch Guidance

Vendor Patch Status: Patch confidence 0/4. The vendor (Edimax) has been contacted but has not responded. There is no evidence of any patch, firmware update, or security advisory from any trusted source. All Edimax BR-6214K devices running firmware 1.40 must be considered vulnerable indefinitely.

Immediate Mitigations (no patch available):

1. Disable remote management: If remote administration is not strictly required, disable it immediately. This removes the primary attack surface for remote exploitation.
2. Restrict management interface access: If remote management is needed, restrict access to trusted IP addresses only via a firewall or access-control list. Place the device management interface on a separate VLAN inaccessible from the internet.
3. Change default credentials: Ensure the administrative account does not use default credentials. Although this does not patch the vulnerability, the CVSS vector requires high privileges (PR:H), which can be severely weakened if default credentials (such as admin/admin — a common default for this device class, not individually confirmed) remain in use.
4. Monitor for exploitation: Deploy the detection rules provided in this report on any sensors, IDS/IPS systems, or SIEM platforms that observe traffic to/from the affected device.

Patch/Upgrade Steps:

1. Check the Edimax support website periodically for firmware updates for the BR-6214K.
2. If a firmware update becomes available, apply it to the device following vendor instructions.
3. If no update arrives, consider decommissioning the device and replacing it with a supported—and regularly patched—router model.

Long-Term Hardening:

1. Adopt a lifecycle management policy that removes unsupported/unpatched devices from production networks.
2. Segregate IoT/network infrastructure devices onto dedicated VLANs with strict egress filtering.
3. Regularly audit network edge devices for firmware versions and security posture.
4. Inventory all network devices and track their support status; replace end-of-life devices proactively.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-82703
2. MITRE CVE Record: https://www.cve.org/CVERecord?id=CVE-2026-82703
3. CWE-77 (Command Injection): https://cwe.mitre.org/data/definitions/77.html
4. ATT&CK Technique T1190 (Exploit Public-Facing Application): https://attack.mitre.org/techniques/T1190/

Threat Actor Campaigns / Exploit-in-the-Wild: The NVD description confirms that an exploit has been released to the public ("The exploit has been released to the public and may be used for attacks"). However, no specific threat actor campaigns or named groups have been publicly attributed to this CVE at the time of writing. The device is not present on the CISA KEV (Known Exploited Vulnerabilities) catalog. Given the public availability of exploit knowledge, the likelihood of exploitation attempts against internet-exposed devices is elevated. IoT botnet operators (e.g., Mirai-variant families) have historically incorporated router vulnerabilities of this class into their propagation modules within days or weeks of public disclosure; enterprises running this device on perimeter networks should assume an elevated risk of automated opportunistic exploitation.