std::vector<uint8_t> cmd = {0x00,0x84,0x00,0x00};  // size()==4
size_t pos = cmd.size() <= 5 ? 4 : 5+cmd[4];  // pos==4
cmd[pos] = 0x08;  // write past end

std::vector<uint8_t> cmd = {0x00,0xD0,0x00,0x00,0x10,  // Lc = 16
                            0xAA,0xBB,0xCC,0xDD,0xEE};  // only 5 data bytes, size()==10
size_t pos = 5 + cmd[4];  // 5 + 0x10 = 21
cmd[pos] = 0x08;  // write past end

    void getResponseWithLE(ResponseApdu& response, const CommandApdu& command) const
    {
        ...
    }

    ResponseApdu transmitBytes(const CommandApdu& command) const
    {
        byte_vector commandBytes = command;
        byte_vector responseBytes(ResponseApdu::MAX_SIZE, 0);
        auto responseLength = DWORD(responseBytes.size());

        SCard(Transmit, cardHandle, &_protocol, commandBytes.data(), DWORD(commandBytes.size()),
              nullptr, responseBytes.data(), &responseLength);

        auto response = toResponse(std::move(responseBytes), responseLength);

        if (response.sw1 == ResponseApdu::WRONG_LE_LENGTH) {
            getResponseWithLE(response, command);
        }
        ...
    }