Executive Summary

[{'type': 'paragraph', 'content': 'CVE-2026-2535 is a command injection vulnerability found in the Comfast CF-N1 V2 router, version 2.6.0.2. It occurs in the function sub_44AB9C within the CGI script at the endpoint /cgi-bin/mbox-config when accessed with specific parameters.'}, {'type': 'paragraph', 'content': "The vulnerability arises because the router improperly handles the 'channel' argument, allowing an attacker to inject arbitrary commands. This happens due to insufficient neutralization of special characters, enabling remote attackers to execute commands on the device by sending specially crafted HTTP POST requests."}, {'type': 'paragraph', 'content': 'The exploit can be launched remotely without authentication, making it a significant security risk. The vendor was contacted but did not respond, and a public proof-of-concept exploit is available.'}] [1, 2]

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Impact Analysis

[{'type': 'paragraph', 'content': "This vulnerability allows remote attackers to execute arbitrary commands on the affected device, which can compromise the device's confidentiality, integrity, and availability."}, {'type': 'list_item', 'content': 'Attackers can take control of the router remotely.'}, {'type': 'list_item', 'content': 'Sensitive information on the device could be exposed or altered.'}, {'type': 'list_item', 'content': 'The device could be disrupted or used as a foothold for further attacks on the network.'}, {'type': 'paragraph', 'content': 'Since the exploit is publicly available and requires no authentication, the risk of exploitation is high.'}] [1, 2]

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by monitoring for HTTP POST requests targeting the endpoint /cgi-bin/mbox-config with parameters method=SET and section=ptest_channel, especially those manipulating the "channel" argument.'}, {'type': 'paragraph', 'content': 'Since the exploit involves command injection via specially crafted HTTP requests, you can detect attempts by capturing and analyzing network traffic for suspicious POST requests to this endpoint.'}, {'type': 'paragraph', 'content': 'Suggested commands include using network monitoring tools such as tcpdump or Wireshark to filter HTTP POST requests to the vulnerable path. For example:'}, {'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 '/cgi-bin/mbox-config?method=SET&section=ptest_channel'"}, {'type': 'list_item', 'content': 'Using curl or similar tools to test the endpoint manually by sending crafted POST requests to check for command injection behavior.'}, {'type': 'paragraph', 'content': 'Additionally, reviewing device logs for unusual commands or unexpected behavior related to the "channel" parameter can help identify exploitation attempts.'}] [1, 2]

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Mitigation Strategies

There are no official patches or mitigations available from the vendor as they did not respond to the disclosure.

Immediate mitigation steps include restricting access to the vulnerable endpoint by implementing network-level controls such as firewall rules to block external access to /cgi-bin/mbox-config?method=SET&section=ptest_channel.

Consider disabling or restricting the affected functionality if possible.

Monitor the device for suspicious activity and unauthorized commands.

Ultimately, it is recommended to replace the affected Comfast CF-N1 V2 device with a secure alternative to fully mitigate the risk.

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