Executive Summary

CVE-2026-30649 is a pre-authentication stack buffer overflow vulnerability in the VIVOTEK FD8136 camera running firmware version FD8136-VVTK-0300a. The flaw exists in the /cgi-bin/anonymous/setparam.cgi endpoint, which is a symlink to set_getparam.cgi.

The vulnerability occurs because the set_getparam.cgi handler copies the raw POST request body into a heap buffer without enforcing size limits, then forwards it to setparam_cgi. Although setparam_cgi performs basic validation, it does not check the length before passing the data to set_get_param, where the attacker-controlled input is written into a fixed-size stack buffer using sprintf without bounds checking.

A sufficiently large POST request body overflows the stack buffer, overwriting the saved return address and enabling arbitrary code execution. Since the endpoint is accessible without authentication, this vulnerability can be exploited by unauthenticated attackers.

The heap is non-randomized and executable, allowing attackers to place shellcode in the heap buffer and overwrite the return address with a fixed heap address. The binary runs as root with no stack canaries or other memory protections, making exploitation straightforward.

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Impact Analysis

This vulnerability allows unauthenticated remote attackers to execute arbitrary code with root privileges on the affected VIVOTEK FD8136 camera device.

Exploitation can lead to full compromise of the device, including unauthorized control, data theft, disruption of device functionality, or using the device as a foothold for further attacks within a network.

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Detection Guidance

This vulnerability can be detected by checking for the presence of the vulnerable VIVOTEK FD8136 camera firmware version FD8136-VVTK-0300a or similar versions running the affected set_getparam.cgi component.

Since the vulnerability is triggered by sending a specially crafted POST request to the /cgi-bin/anonymous/setparam.cgi endpoint, detection can involve monitoring network traffic for unusual or oversized POST requests to this endpoint.

Suggested commands to detect the vulnerability or attempt exploitation (for testing in a controlled environment) include using curl or similar tools to send POST requests to the endpoint and observe responses or crashes.

• curl -X POST http://<device-ip>/cgi-bin/anonymous/setparam.cgi -d '<payload>'
• Use network monitoring tools (e.g., tcpdump, Wireshark) to filter HTTP POST requests to /cgi-bin/anonymous/setparam.cgi and check for abnormal payload sizes.

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Mitigation Strategies

Immediate mitigation steps include restricting access to the vulnerable endpoint /cgi-bin/anonymous/setparam.cgi to trusted networks or IP addresses only, effectively blocking unauthenticated remote access.

If possible, disable or restrict the use of the set_getparam.cgi component until a patch or firmware update is available.

Monitor network traffic for suspicious POST requests targeting the vulnerable endpoint and block or alert on such activity.

Contact VIVOTEK for firmware updates or patches addressing this vulnerability and apply them as soon as they become available.

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Compliance Impact

The provided information does not specify how the CVE-2026-30649 vulnerability impacts compliance with common standards and regulations such as GDPR or HIPAA.

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