Executive Summary

CVE-2026-36800 is a buffer overflow vulnerability found in the Tenda G0 router firmware, specifically in the formIPMacBindDel function.

This function processes HTTP requests and uses the IPMacBindIndex parameter from user input without proper bounds checking during a strcpy operation.

An attacker can exploit this by sending a crafted HTTP request with an excessively long IPMacBindIndex parameter (for example, 888 or more characters), which causes a buffer overflow.

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Impact Analysis

Exploiting this vulnerability can cause a Denial of Service (DoS) condition on the affected device.

This may lead to process crashes or instability of the Tenda G0 router, potentially disrupting network connectivity and device availability.

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Detection Guidance

This vulnerability can be detected by monitoring for unusually long HTTP requests targeting the formIPMacBindDel function, specifically those containing the IPMacBindIndex parameter with an excessively long value (e.g., 888 or more characters).

A practical detection method is to capture HTTP traffic to the Tenda G0 router and filter requests that include the IPMacBindIndex parameter with a length exceeding normal bounds.

• Use a network packet capture tool like tcpdump or Wireshark to capture HTTP requests to the router.
• Example tcpdump command to capture HTTP traffic to the router's IP (replace <router_ip>): tcpdump -A -s 0 host <router_ip> and tcp port 80
• Use grep or similar tools to search captured traffic for 'IPMacBindIndex=' parameters with long values, for example: grep -Eo 'IPMacBindIndex=[^&]{888,}' capturefile

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Mitigation Strategies

Immediate mitigation steps include restricting access to the router's HTTP management interface to trusted networks or IP addresses to prevent attackers from sending crafted requests.

Additionally, monitoring and blocking HTTP requests with abnormally long IPMacBindIndex parameters can help prevent exploitation.

If available, update the router firmware to a version that patches this buffer overflow vulnerability.

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