Tenda AC15 US_AC15V1.0BR_V15.03.05.20_multi_TDE01.bin is vulnerable to Buffer Overflow. The stack overflow vulnerability lies in the /goform/setpptpservercfg interface of the web. The sent post data startip and endip are copied to the stack using the sanf function, resulting in stack overflow. Similarly, this vulnerability can be used together with CVE-2021-44971