First of all, according to John Mueller, sitewide links don’t harm the website that contains the sitewide links and the website that receive the sitewide links. In a Google hangout in mentioned that the sitewide links should not be disavowed. This simple statement really means that no penalty can be generated by sitewide links. However, I want to warn my readers here. If the said link is a spammy website, you can penalize your whole website because a web page is linked to a spammy web page (also called bad neighborhood).
We also know that if you had a sitewide link in a footer or in a sidebar, this does not send a massive amount of Google juice to the recipient. The number of google juice decreases as the number of link occurrence increases. This means that after it is useless to have 100 links in the footer. This may send as much google juice as 5 links.