Executive Summary

[{'type': 'paragraph', 'content': 'CVE-2026-4172 is a stack-based buffer overflow vulnerability found in the TRENDnet TEW-632BRP router, version 1.010B32. It exists in the HTTP POST request handler within the /ping_response.cgi file. The vulnerability arises from improper handling of the "ping_ipaddr" argument, which when manipulated with crafted input, causes a stack overflow.'}, {'type': 'paragraph', 'content': 'An authenticated attacker can exploit this by sending a specially crafted POST request containing an overly long string in the ping_ipaddr parameter. The vulnerability is due to insufficient length validation before copying the input into a stack variable using an unsafe function, leading to the overflow.'}, {'type': 'paragraph', 'content': 'This flaw can lead to denial of service or potentially allow arbitrary code execution on the device.'}] [1, 2, 3]

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Impact Analysis

Exploitation of this vulnerability can compromise the confidentiality, integrity, and availability of the affected device.

• Denial of Service (DoS) by crashing the device.
• Potential arbitrary code execution, allowing an attacker to run malicious code on the device.
• Remote exploitation is possible but requires authentication.

Since the vendor has not provided any patches or mitigations, affected users are advised to consider replacing the product to avoid these risks.

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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 authenticated HTTP POST requests to the /ping_response.cgi endpoint containing an unusually long or malformed ping_ipaddr parameter.'}, {'type': 'paragraph', 'content': "A practical detection method involves capturing and inspecting HTTP POST traffic to the device's web interface, specifically looking for the ping_ipaddr argument in requests to /ping_response.cgi."}, {'type': 'paragraph', 'content': 'Since exploitation requires authentication, detection can also include reviewing device logs for suspicious authenticated POST requests with abnormal ping_ipaddr values.'}, {'type': 'list_item', 'content': 'Use network packet capture tools like tcpdump or Wireshark to filter HTTP POST requests to /ping_response.cgi.'}, {'type': 'list_item', 'content': "Example tcpdump command to capture relevant traffic: tcpdump -i <interface> -A 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' | grep 'POST /ping_response.cgi'"}, {'type': 'list_item', 'content': 'Use curl or similar tools to test the endpoint with crafted ping_ipaddr parameters to verify if the device is vulnerable.'}] [2, 3]

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Mitigation Strategies

[{'type': 'paragraph', 'content': "Immediate mitigation steps include restricting access to the affected device's web interface to trusted users only, as exploitation requires authentication."}, {'type': 'paragraph', 'content': 'Since no official patch or vendor response is available, consider replacing the affected TRENDnet TEW-632BRP device with a more secure alternative.'}, {'type': 'paragraph', 'content': "Implement network-level controls such as firewall rules to limit access to the device's management interface."}, {'type': 'paragraph', 'content': 'If possible, disable or restrict the HTTP POST handler for /ping_response.cgi or apply input validation filters to the ping_ipaddr parameter to prevent buffer overflow conditions.'}, {'type': 'paragraph', 'content': 'Monitor device logs for suspicious activity and unauthorized POST requests to the vulnerable endpoint.'}] [1, 2]

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