CVE-2026-19963

Executive Summary

CVE-2026-19963 describes a command injection vulnerability affecting Edimax EW-7478APC devices running firmware version 1.04. This flaw, found in the stainfo function of the /goform/stainfo file, allows an attacker to inject arbitrary operating system commands through manipulation of the interface argument. The vulnerability is remotely exploitable and requires low privileges for successful execution, potentially leading to unauthorized command execution and compromise of the device. An exploit for this vulnerability has been publicly disclosed, increasing the urgency for mitigation given the absence of an official patch.

Technical Analysis

The vulnerability, identified as CVE-2026-19963, is a classic command injection (CWE-74) present in the Edimax EW-7478APC wireless access point, specifically in firmware version 1.04. The core of the flaw resides within the stainfo function, which is exposed via the web interface at the /goform/stainfo endpoint. This function is designed to process the interface argument, likely to retrieve or display status information related to a network interface.

The command injection occurs due to insufficient input sanitization or validation of the interface parameter. When an attacker supplies specially crafted input containing operating system command delimiters (e.g., semicolons, backticks, pipe symbols) followed by arbitrary commands, the device's underlying operating system executes these injected commands. The vulnerability is remotely exploitable over the network (AV:N) and requires low privileges (PR:L), suggesting that an attacker either needs to be authenticated to the device's web interface or can leverage default/weak credentials to initiate the attack. No user interaction is required (UI:N).

The scope of the attack is 'Changed' (S:C), indicating that the vulnerability allows an attacker to affect resources beyond the security scope of the vulnerable component itself, typically leading to system-level command execution. While the CVSS score indicates low impact on confidentiality (C:L), integrity (I:L), and availability (A:L), a successful command injection can often be escalated to achieve higher impact, including full system compromise, data exfiltration, or denial of service, depending on the privileges of the executing process and subsequent attacker actions. The public disclosure of exploit details makes this a high-risk vulnerability for affected devices.

Exploitation Scenarios

Exploitation of CVE-2026-19963 involves a remote attacker leveraging the command injection flaw in the Edimax EW-7478APC device.

1. Reconnaissance/Target Identification: An attacker identifies vulnerable Edimax EW-7478APC devices (firmware 1.04) exposed to the internet or an accessible internal network. This can be achieved using network scanning tools or public search engines like Shodan with dorks such as http.title:"Edimax EW-7478APC" or html:"Edimax EW-7478APC". The attacker then identifies the web administration interface, typically accessed via HTTP or HTTPS.

2. Authentication (Low Privileges): Given the PR:L (Low Privileges) CVSS vector component, the attacker would first need to gain low-level authenticated access to the device's web interface. This might involve:

   • Leveraging default administrative credentials (if not changed by the user).
   • Guessing weak credentials.
   • Exploiting another, pre-authentication vulnerability (though not described by this CVE). Once authenticated, the attacker gains access to endpoints like /goform/stainfo.

3. Triggering the Flaw: The authenticated attacker constructs a malicious HTTP request (typically GET or POST) targeting the /goform/stainfo endpoint. Within this request, the interface argument is crafted to include operating system command injection payloads. For example, instead of a legitimate interface name, the attacker injects characters that break out of the intended command context and append arbitrary commands.

   • Example: GET /goform/stainfo?interface=eth0;id; HTTP/1.1
   • Example: GET /goform/stainfo?interface=eth0%3Bid%3B HTTP/1.1 (URL-encoded semicolon)

4. Payload Execution: The device's web server, upon receiving this request, passes the malformed interface argument to the stainfo function. Due to the lack of proper sanitization, the injected commands (e.g., id to determine the user context, cat /etc/passwd to dump sensitive files, or commands to establish a reverse shell) are executed on the underlying operating system. The commands are typically executed with the privileges of the web server process, which could range from a dedicated low-privilege user to root, depending on the device's configuration.

5. Post-Exploitation Impact: Successful command injection grants the attacker remote code execution capabilities. This can lead to various post-exploitation activities, including:

   • Confidentiality (C:L): Reading sensitive system configuration files, credentials, or network information. While rated 'Low', an attacker can potentially exfiltrate significant data over time.
   • Integrity (I:L): Modifying system configuration, creating new user accounts, or implanting backdoors.
   • Availability (A:L): Executing commands that could disrupt service, such as rebooting the device or deleting critical files.
   • Network Pivoting: Establishing a foothold within the target network to launch further attacks against other internal systems.
   • Persistence: Installing persistent backdoors or modifying startup scripts to maintain access even after reboots.

Despite the CVSS vector's 'Low' rating for C, I, and A, the ability to execute arbitrary commands remotely with low privileges fundamentally compromises the device and provides a strong foundation for escalating privileges and achieving a much higher impact.

Impact Assessment

The impact of CVE-2026-19963 on Edimax EW-7478APC 1.04 devices is significant due to the nature of command injection and the public availability of exploit details. Organizations utilizing these devices face a direct threat of remote compromise.

Business Impact:

• Device Compromise: Full control over the wireless access point, potentially allowing an attacker to manipulate network configurations, redirect traffic, or capture network communications.
• Network Breach: The compromised access point can serve as a pivot point for attackers to gain access to the internal network, bypassing perimeter defenses. This can lead to unauthorized access to sensitive data, internal systems, and other connected devices.
• Data Exfiltration: Although rated C:L (Low Confidentiality Impact), an attacker with RCE can read and exfiltrate device-specific configurations, user credentials, network topology information, and potentially data passing through the access point.
• Service Disruption: Malicious commands can lead to device instability, reboots, or complete shutdown, resulting in denial of service and disruption to network connectivity for users dependent on the access point.
• Reputational Damage: For service providers or businesses relying on these devices, a public compromise can lead to a loss of customer trust and reputational harm.

Affected Systems and Blast Radius: The primary affected systems are Edimax EW-7478APC devices running firmware version 1.04. The blast radius extends to any systems connected to or relying on these compromised access points.

• Network Clients: Users connected to the compromised access point may have their traffic monitored or redirected.
• Internal Network: If the access point is configured within an enterprise network, the attacker can use it to launch lateral movement attacks.
• Managed Networks: In environments where multiple Edimax devices are managed centrally, a compromise of one could potentially aid in attacking others if network segmentation is poor.

CVSS Subscore Analysis:

• AV:N (Attack Vector: Network): Indicates that the vulnerability is exploitable remotely over a network connection, making it widely accessible to attackers.
• AC:L (Attack Complexity: Low): Exploitation requires no specialized conditions or complex timing, making it straightforward for an attacker to execute.
• PR:L (Privileges Required: Low): An attacker needs only low-level privileges (e.g., authenticated access, default credentials) to exploit the flaw. This significantly lowers the barrier to entry for attackers.
• UI:N (User Interaction: None): No user intervention is required on the target device, allowing for silent and automated exploitation.
• S:C (Scope: Changed): The vulnerability allows an attacker to affect resources beyond the security scope of the vulnerable component, meaning they can execute commands at the operating system level, which is a critical aspect of command injection.
• C:L (Confidentiality Impact: Low): While rated low, an attacker can access some sensitive information. In practice, command injection often allows access to a broader range of confidential data, which could be escalated.
• I:L (Integrity Impact: Low): An attacker can make some unauthorized modifications. Similar to C:L, the practical impact of arbitrary command execution can be much higher than 'Low'.
• A:L (Availability Impact: Low): An attacker can cause some disruption to service. Again, command injection could lead to complete system unavailability.

The 'Low' ratings for C, I, A may reflect the typical impact of limited command execution without further post-exploitation steps, or assume some default system hardening. However, the S:C (Changed Scope) and AV:N/AC:L/PR:L components highlight the ease and reach of the attack, making even 'Low' impacts dangerous given the potential for escalation.

Detection Guidance

Sigma Rule

title: Edimax EW-7478APC stainfo Command Injection Attempt
id: 59e2b10a-3c4f-4d5d-9a99-9e8c3f4e3b7b
status: experimental
description: Detects attempts to exploit CVE-2026-19963, a command injection vulnerability in Edimax EW-7478APC firmware 1.04 via the /goform/stainfo endpoint.
author: valtersit.com
date: 2024/01/23
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-19963
logsource:
  category: webserver
  product: http_access_logs
detection:
  selection:
    cs-uri-stem: '/goform/stainfo'
    cs-uri-query|contains:
      - 'interface='
      - ';'
      - '|'
      - '&'
      - '`'
      - '$('
      - '%3B' # URL-encoded semicolon
      - '%7C' # URL-encoded pipe
      - '%26' # URL-encoded ampersand
      - '%60' # URL-encoded backtick
  condition: selection
level: high
tags:
  - attack.injection
  - attack.command_and_control
  - cve.2026.19963
  - cwe.74

YARA Rule

rule Edimax_EW_7478APC_CVE_2026_19963_Exploit_Traffic
{
  meta:
    author = "valtersit.com"
    date = "2024-01-23"
    description = "Detects HTTP traffic attempting to exploit CVE-2026-19963 in Edimax EW-7478APC via command injection."
    cve = "CVE-2026-19963"
    severity = "HIGH"
    reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-19963"
  strings:
    $http_method = "GET" nocase ascii wide
    $uri_path = "/goform/stainfo?" ascii wide
    $param_name = "interface=" ascii wide
    $payload_char1 = ";" ascii wide
    $payload_char2 = "|" ascii wide
    $payload_char3 = "&" ascii wide
    $payload_char4 = "`" ascii wide
    $payload_char5 = "$(" ascii wide
    $payload_encoded1 = "%3B" ascii wide // URL-encoded semicolon
    $payload_encoded2 = "%7C" ascii wide // URL-encoded pipe
    $payload_encoded3 = "%26" ascii wide // URL-encoded ampersand
    $payload_encoded4 = "%60" ascii wide // URL-encoded backtick

  condition:
    $http_method in (0..100) and $uri_path in (0..200) and $param_name in (0..300) and
    ($payload_char1 or $payload_char2 or $payload_char3 or $payload_char4 or $payload_char5 or
     $payload_encoded1 or $payload_encoded2 or $payload_encoded3 or $payload_encoded4)
}

Suricata IDS Rule

alert http any any -> any any (msg:"ET EXPLOIT Edimax EW-7478APC CVE-2026-19963 Command Injection Attempt"; flow:established,to_server; http.method; content:"GET"; http.uri; pcre:"/goform/stainfo\?.*interface=[^&]*(;|\x253B|\||\x257C|&|\x2526|`|\x2560|\$\(|\x2524\x2528)/i"; classtype:web-application-attack; sid:20261996301; rev:1;)

Elastic Detection

webserver.access where
  url.path == "/goform/stainfo" and
  url.query_string : ("interface=*", "*;*", "*|*", "*&*", "*`*", "*$(*", "*%3B*", "*%7C*", "*%26*", "*%60*", "*%24%28*")

Splunk SPL Query

sourcetype="web_access_logs" uri_path="/goform/stainfo"
| regex uri_query="interface=[^&]*(;|%3B|\||%7C|&|%26|`|%60|\$\(|\%24\%28)"
| table _time, src_ip, dest_ip, uri_path, uri_query, user_agent

Wazuh OSSEC Rule

<group name="web,attack,command_injection,">
  <rule id="100001" level="12">
    <if_sid>31100</if_sid> <!-- Base rule for web access logs -->
    <url>/goform/stainfo</url>
    <var name="cmd_injection_chars">(\;|\%3B|\||\%7C|&amp;|\%26|`|\%60|\$\(|\%24\%28)</var>
    <regex type="pcre">interface=[^&amp;]*${cmd_injection_chars}</regex>
    <description>Edimax EW-7478APC CVE-2026-19963 Command Injection Attempt Detected</description>
    <group>attack,web_attack,vulnerability,</group>
    <options>no_full_log</options>
  </rule>
</group>

Mitigation & Patch Guidance

As of the current intelligence, CVE-2026-19963 affecting Edimax EW-7478APC firmware 1.04 is an UNPATCHED vulnerability (Patch Confidence: 0/4). The vendor was contacted but has not responded, leaving affected devices exposed. Immediate and proactive mitigation strategies are crucial to minimize risk.

1. Immediate Mitigations (Temporary Measures):

   • Network Segmentation: Isolate Edimax EW-7478APC devices on a separate network segment with strict access controls, preventing unauthorized access from untrusted networks (e.g., the internet) to the device's administrative interface.
   • Access Control Lists (ACLs): Implement firewall rules to restrict access to the web administration interface (typically HTTP/HTTPS ports 80/443 or others if customized) of the EW-7478APC devices. Only allow access from trusted management IP addresses or networks.
   • Web Application Firewall (WAF): Deploy a WAF in front of any exposed Edimax devices. Configure WAF rules to detect and block requests to /goform/stainfo that contain known command injection characters (e.g., ;, |, &, ``, $(), or their URL-encoded equivalents) within the interface parameter.
   • Disable or Restrict Functionality: If feasible and not critical for operations, explore options to disable or restrict access to the /goform/stainfo endpoint directly on the device or via proxying rules. This is a high-impact workaround and must be tested thoroughly.
   • Monitor for Exploitation: Implement the provided detection guidance (Sigma, YARA, Suricata, Elastic, Splunk, Wazuh rules) to actively monitor network traffic and logs for signs of attempted or successful exploitation.

2. Patch/Upgrade Steps (No Patch Available):

   • Vendor Monitoring: Regularly monitor the official Edimax support website, security advisories, and industry news for any official patches or firmware updates related to this specific CVE.
   • Upgrade if Available: If a patched firmware version (higher than 1.04) becomes available, plan for an urgent upgrade following vendor-provided instructions. Prioritize critical deployments.
   • Consider Replacement: Given the lack of vendor response and patch, organizations should consider a phased replacement of affected Edimax EW-7478APC devices with products from vendors with a stronger security posture and active support for their products.

3. Long-Term Hardening:

   • Secure Configuration Review: Conduct regular security audits of all network devices, including access points, to ensure they are configured securely. This includes changing all default credentials to strong, unique passwords.
   • Principle of Least Privilege: Ensure that network devices and services operate with the minimum necessary privileges.
   • Regular Vulnerability Scanning: Implement a routine vulnerability management program to identify and address known vulnerabilities across all network assets.
   • Endpoint Detection and Response (EDR): While access points often don't support EDR agents, ensure that devices connected through the access point have robust EDR solutions to detect post-exploitation activities.
   • Employee Awareness: Educate staff on the importance of strong passwords and recognizing phishing attempts that might target administrative credentials for network devices.

References

1. NVD - CVE-2026-19963: https://nvd.nist.gov/vuln/detail/CVE-2026-19963
2. CWE-74 - Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Command Injection'): https://cwe.mitre.org/data/definitions/74.html
3. Edimax Official Website: https://www.edimax.com/ (Monitor for advisories or firmware updates)
4. MITRE ATT&CK - T1190 Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/