CVE-2026-2873 Details

A stack-based buffer overflow vulnerability has been identified in the Tenda A21 router running firmware version 1.0.0.0. The issue arises in the Wi-Fi scheduling configuration endpoint '/goform/openSchedWifi', specifically within the 'setSchedWifi' function. This function uses 'websGetVar' to retrieve user-controlled parameters 'schedStartTime' and 'schedEndTime', which are then copied into a fixed-size heap-allocated buffer of 25 bytes using the unsafe 'strcpy' function. The lack of input length validation allows attackers to overflow the buffer, potentially leading to memory corruption, a denial-of-service condition, or arbitrary code execution. The vulnerability can be exploited remotely, and a public exploit is available.

To address this vulnerability, it is recommended to use safer string copy functions that include length checks, validate the format and length of time-related inputs, and ensure that allocated buffers are large enough to accommodate all possible valid inputs plus a null terminator.