In a blog post yesterday on the Google Webmaster Central Blog, Agnieszka Łata of the Trust & Safety Search Team and Webmaster Relations Specialist Eric Kuan reminded webmasters to avoid breaking the Webmaster Guidelines with links in widgets.
Widgets have existed on the web for decades, and similarly it is not news as such that Google are against low quality widely distributed links.
However it is important that any webmasters that make use of widgets note these recommendations.
Google recommend to avoid the creation of "keyword-rich, hidden or low-quality links" distributed across multiple sites.
The following images are provided as examples of the types of links that Google are discouraging (filenames unchanged):
If you do have these types of links in your widget Google's recommendation is to add a rel="nofollow" tag.
Webmasters that do not do this could receive a manual action warning via Search Console.
We at Search Candy would recommend against using such over-optimised links in any circumstances, whether in a widget or not.
Similarly if you have a widget on your site that contains an over-optimised link pointing to another website you might want to consider nofollowing the link or removing the widget.
You can view the post from Google here.