Executive Summary

[{'type': 'paragraph', 'content': "CVE-2026-4567 is a stack-based buffer overflow vulnerability found in the Tenda A15 router firmware version 15.13.07.13. It occurs in the UploadCfg function of the /cgi-bin/UploadCfg endpoint. The vulnerability arises because the input argument 'File' is not properly validated or limited in size, allowing an attacker to overflow the stack buffer."}, {'type': 'paragraph', 'content': 'This flaw can be exploited remotely without any authentication, meaning an attacker can send specially crafted requests to the device and trigger the overflow.'}, {'type': 'paragraph', 'content': 'Exploitation of this vulnerability may lead to arbitrary code execution or denial of service on the affected device.'}] [1, 2]

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Impact Analysis

This vulnerability can have severe impacts including allowing a remote attacker to execute arbitrary code on the affected Tenda A15 router without any authentication.

Such unauthorized code execution could lead to full compromise of the device, enabling the attacker to control the router, intercept or manipulate network traffic, or disrupt network services.

Additionally, exploitation can cause denial of service, making the device unavailable to legitimate users.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability involves an unauthenticated stack-based buffer overflow in the /cgi-bin/UploadCfg endpoint of the Tenda A15 router firmware version 15.13.07.13. Detection would typically involve monitoring for suspicious HTTP requests targeting the /cgi-bin/UploadCfg path with unusually large or malformed File arguments.'}, {'type': 'paragraph', 'content': 'Since no specific detection commands or signatures are provided in the available resources, general network monitoring tools like tcpdump or Wireshark can be used to capture HTTP traffic to the device, filtering for requests to /cgi-bin/UploadCfg.'}, {'type': 'list_item', 'content': "Use tcpdump to capture HTTP requests to the vulnerable endpoint: tcpdump -i <interface> 'tcp port 80 and (((ip dst <router_ip>) and (tcp[32:4] = 0x2f636769)))'"}, {'type': 'list_item', 'content': 'Use curl or similar tools to test the endpoint manually by sending crafted requests to /cgi-bin/UploadCfg and observe the device behavior.'}, {'type': 'paragraph', 'content': 'However, no specific detection scripts or commands are provided in the available information.'}] [1, 2]

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Mitigation Strategies

Immediate mitigation steps are not explicitly detailed in the provided resources. However, general best practices for this type of vulnerability include:

• Restrict network access to the vulnerable device, especially blocking external access to the /cgi-bin/UploadCfg endpoint.
• Apply any available firmware updates or patches from the vendor addressing this vulnerability.
• If no patch is available, consider disabling the vulnerable service or CGI endpoint if possible.
• Monitor the device for unusual behavior or crashes that may indicate exploitation attempts.

Since the vulnerability allows remote unauthenticated exploitation, limiting exposure and applying vendor fixes are critical.

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