Tenda AC21 Buffer Overflow Vulnerability in Parent Control Information Management

A buffer overflow vulnerability has been identified in the Tenda AC21 router running firmware version V16.03.08.16. The issue arises in the '/goform/saveParentControlInfo' endpoint, where the 'deviceId' parameter is processed by the 'httpd' binary. The vulnerability allows for a heap-based buffer overflow, which can be exploited to cause a denial-of-service condition.

Impact

Exploitation of this vulnerability leads to a heap-based buffer overflow, causing a segmentation fault and disrupting the service.

Reproduction

The vulnerability can be reproduced by sending a POST request to '/goform/saveParentControlInfo' with a 'deviceId' parameter that exceeds the allocated buffer size. The 'deviceId' can be filled with a large amount of data, which will be copied into a heap buffer without proper bounds checking, leading to the buffer overflow.