Executive Summary

[{'type': 'paragraph', 'content': "CVE-2026-3696 is a critical OS command injection vulnerability found in the TOTOLINK N300RH V4 router, specifically in firmware version V6.1c.1353_B20190305. The flaw exists in the setWiFiWpsConfig function of the CGI handler component, accessible via the router's web management interface at /cgi-bin/cstecgi.cgi."}, {'type': 'paragraph', 'content': "The vulnerability arises because the function processes user input from the HTTP parameter 'PIN' without any validation or sanitization, embedding it directly into a shell command string that is executed with root privileges. This allows a remote attacker with network access to the router’s web interface to inject arbitrary shell commands."}, {'type': 'paragraph', 'content': 'Exploitation requires no authentication and can be performed remotely, potentially leading to full compromise of the router and control over the connected network.'}] [1, 2, 3]

Useful 0 Not Useful 0

Impact Analysis

This vulnerability allows a remote attacker to execute arbitrary OS commands on the affected router with root privileges without any authentication.

As a result, the attacker can fully compromise the router, gaining control over its configuration and potentially the entire connected network.

This can lead to loss of confidentiality, integrity, and availability of the device and network resources, enabling further attacks such as data interception, network manipulation, or launching attacks on other connected systems.

Useful 0 Not Useful 0

Compliance Impact

I don't know

Useful 0 Not Useful 0

Detection Guidance

[{'type': 'paragraph', 'content': "This vulnerability can be detected by monitoring for suspicious HTTP POST requests to the router's web management interface, specifically targeting the endpoint /cgi-bin/cstecgi.cgi with parameters related to WPS PIN configuration."}, {'type': 'paragraph', 'content': 'A detection method involves checking for HTTP requests containing the parameter "PINPBCRadio" set to "1" and the "PIN" parameter containing suspicious shell metacharacters such as `;`, `|`, `&`, backticks (`), or $().'}, {'type': 'paragraph', 'content': 'Example command to detect such attempts using network traffic capture tools like tcpdump or tshark:'}, {'type': 'list_item', 'content': "tcpdump -A -s 0 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' | grep -E 'PINPBCRadio=1|PIN=.*[;|&`$()]'"}, {'type': 'paragraph', 'content': 'Alternatively, using curl to test the vulnerability by sending a crafted POST request (for detection or proof-of-concept):'}, {'type': 'list_item', 'content': "curl -X POST http://[router-ip]/cgi-bin/cstecgi.cgi -d 'PINPBCRadio=1&PINMode=&PIN=12345678`id`'"}, {'type': 'paragraph', 'content': 'If the router executes the injected command (e.g., returns output of `id`), it confirms the presence of the vulnerability.'}] [3]

Useful 0 Not Useful 0

Mitigation Strategies

[{'type': 'paragraph', 'content': 'Currently, no known countermeasures or mitigations exist for this vulnerability in the affected firmware version.'}, {'type': 'paragraph', 'content': 'The recommended immediate step is to replace the affected Totolink N300RH router with an alternative device that is not vulnerable.'}, {'type': 'paragraph', 'content': "Additionally, if possible, disable remote management access to the router's web interface to reduce exposure."}, {'type': 'paragraph', 'content': "Monitor network traffic for exploitation attempts and restrict network access to the router's management interface to trusted hosts only."}] [2]

Useful 0 Not Useful 0