CVE-2026-105284

Executive Summary

CVE-2026-105284 is a critical improper authorization vulnerability (CWE-266) in the Totolink A3002MU router, specifically within the sub_40FCFC function of the /bin/boa web server binary. The flaw allows a remote, unauthenticated attacker to manipulate authentication checks and gain improper authorization to protected functionality. With a CVSS score of 10.0 and a public exploit available, any internet-exposed A3002MU device running firmware version 1.0.0-B20230403.1455 is at immediate risk of full compromise.

Technical Analysis

The vulnerability resides in the Boa web server component (/bin/boa), which handles HTTP requests for the device's administrative interface. The affected function, sub_40FCFC, is part of the authentication check component. The NVD description states that "executing a manipulation can lead to improper authorization," indicating that an attacker can bypass or subvert authentication logic to perform actions without proper credentials.

CWE-266 (Incorrect Authorization) encompasses flaws where the system fails to correctly verify that a user is authorized to perform an action. In this context, the authentication check implemented in sub_40FCFC can be manipulated—likely through crafted HTTP requests or parameter injection—to grant unauthorized access. The attack vector is network-accessible (AV:N), requires no privileges (PR:N) or user interaction (UI:N), and has a scope change (S:C), meaning the vulnerability can impact resources beyond the vulnerable component's security authority. The impact to confidentiality, integrity, and availability is high (C:H/I:H/A:H), reflecting that an attacker could read sensitive data, modify device configuration, and disrupt services.

Because the device is a consumer-grade router, successful exploitation could lead to full administrative control, enabling attackers to intercept or redirect traffic, join the device to a botnet, or pivot into the local network. The public availability of exploit code lowers the barrier to entry, making widespread scanning and exploitation likely.

Exploitation Scenarios

No public PoC details are available in the provided data; however, the NVD description confirms that an exploit has been made available to the public. The attack chain is inferred from the vulnerability class (improper authorization) and the affected component (Boa web server authentication check).

1. Reconnaissance/Target Identification: Attackers scan the internet for exposed Totolink A3002MU devices using Shodan dorks such as product:"TOTOLINK A3002MU" or http.title:"TOTOLINK". The device's web interface is typically accessible on ports 80 or 443, or via alternative management ports.

2. Triggering the Flaw: The attacker sends crafted HTTP requests to the device's web server. The specific manipulation likely involves bypassing the authentication check in sub_40FCFC by altering request parameters, cookies, or session tokens. Since the function is part of the authentication check, the attacker may exploit insufficient validation of user-supplied input that determines authorization state, effectively tricking the server into granting access without valid credentials.

3. Payload/Execution Method: At the vulnerability-class level, the attacker exploits the improper authorization to access privileged endpoints (e.g., configuration pages, command execution interfaces) that are normally restricted. This could involve directly invoking administrative functions or modifying device settings through the web interface. No specific code patterns or hypothetical function names are assumed beyond the explicitly mentioned sub_40FCFC.

4. Post-Exploitation Impact: With unauthorized access, the attacker can change administrative passwords, modify DNS settings, enable remote management, or upload malicious firmware. The scope change (S:C) indicates that the attacker may leverage the compromised router to affect other systems on the network, such as conducting man-in-the-middle attacks, redirecting traffic, or using the device as a proxy for further attacks.

Impact Assessment

The CVSS 3.1 base score of 10.0 (Critical) reflects maximum severity across all metrics. The network attack vector (AV:N) means exploitation can occur remotely without physical access. Low attack complexity (AC:L) and no privileges required (PR:N) or user interaction (UI:N) make the vulnerability trivial to exploit. The scope change (S:C) indicates that a compromised router can impact other components, such as connected devices or upstream networks. High confidentiality, integrity, and availability impacts (C:H/I:H/A:H) mean attackers can access sensitive data, alter system configurations, and cause denial of service.

Business impact includes complete loss of control over the affected router, potential data breaches via traffic interception, and use of the device as a foothold for lateral movement. For enterprises, unpatched A3002MU devices in branch offices or remote locations could serve as entry points into corporate networks. The blast radius extends to any network segment the router serves, including IoT devices, workstations, and servers.

Detection Guidance

Sigma Rule

title: Totolink A3002MU Improper Authorization Exploitation Attempt
id: 8f4c3b2a-1d5e-4f7a-9b8c-0d1e2f3a4b5c
status: experimental
description: Detects attempts to exploit improper authorization in Totolink A3002MU web interface
author: Threat Intelligence Team
date: 2026-01-01
logsource:
  category: webserver
  product: totolink
detection:
  selection:
    cs-method: 'GET'
    cs-uri-stem:
      - '/boafrm/*'
      - '/cgi-bin/*'
  filter:
    sc-status: 200
  condition: selection and filter
falsepositives:
  - Legitimate administrative access
level: high

YARA Rule

rule CVE_2026_105284_Totolink_A3002MU
{
    meta:
        description = "Detects Totolink A3002MU firmware with vulnerable Boa binary"
        author = "Threat Intelligence Team"
        date = "2026-01-01"
        reference = "CVE-2026-105284"
        hash = "unknown"
    strings:
        $boa = "/bin/boa"
        $func = "sub_40FCFC"
        $ver = "1.0.0-B20230403.1455"
    condition:
        any of them
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-105284 Totolink A3002MU Improper Authorization Attempt"; flow:to_server,established; content:"/boafrm/"; http_uri; content:"A3002MU"; http_header; classtype:attempted-admin; sid:1000001; rev:1;)

Elastic Detection

sequence by host.id
  [ network where network.protocol == "http" and url.path : "/boafrm/*" and http.response.status_code == 200 ]
  [ network where network.protocol == "http" and url.path : "/cgi-bin/*" and http.response.status_code == 200 ]

Splunk SPL Query

index=web sourcetype=access_combined
| search uri_path="/boafrm/*" OR uri_path="/cgi-bin/*"
| where status=200
| stats count by src_ip, uri_path, status
| where count > 5

Wazuh OSSEC Rule

<group name="totolink,">
  <rule id="100001" level="12">
    <decoded_as>web-accesslog</decoded_as>
    <url>/boafrm/</url>
    <description>CVE-2026-105284: Totolink A3002MU improper authorization attempt</description>
    <mitre>
      <id>T1190</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1. Immediate Mitigations: Disable remote administration on the A3002MU if not required. Restrict access to the web interface to trusted IP addresses via firewall rules. Place the device behind a VPN for administrative access. Monitor for anomalous HTTP requests to /boafrm/ or /cgi-bin/ paths. Consider replacing the device if no patch is forthcoming.

2. Patch/Upgrade Steps: No patch is available from the vendor. Check Totolink's official support page periodically for firmware updates. If a patch is released, apply it immediately.

3. Long-Term Hardening: Segment IoT and consumer-grade routers from critical network assets. Implement network access control (NAC) to prevent unauthorized devices. Regularly audit firmware versions and replace end-of-life equipment. Use threat intelligence feeds to track exploitation attempts.

References

1. NVD – CVE-2026-105284: https://nvd.nist.gov/vuln/detail/CVE-2026-105284
2. MITRE CWE-266: https://cwe.mitre.org/data/definitions/266.html
3. Totolink Official Support: https://www.totolink.net/
4. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog (not listed as of report date)
5. Vendor advisory: Not available.