It’s copyrighted and not released under a CC or other license. I haven’t setup a formal set of terms for it.
If you have a specific use, just ask and I’d be glad to let you use if I think it is appropriate.
Here seems as good a place as any to ask.
Thanks for this answer. For now I only want to know whether I can use it in a blog post about Hugo.
But maybe I’ll have a more specific use. I’ll come back in due time.
If you would like to use the logo in a blog post that’s fine. We encourage people to use it in footers as “powered by Hugo”. I should draft up an official “usage terms” one of these days.
Writing a blog post about Hugo and using the logo in the story to help describe or identify Hugo should fall under Fair Use.
There is no such thing like “fair use” in Germany. We have a ridiculously rigid copyright regime. Some days ago the highest constitutional court in Germany had to decide whether it is legal to use 2 seconds of noise from the band Kraftwerk in a sampling for another musician. Generations of lawyers in Germany live from trolling ordinary people who share pictures on Facebook. (Google for “Abmahnung”) You can even be sued if you use a picture from wikipedia which has a CC license.
But leaving this aside. As a long time evangelist for Open Source Software esp. Python and Plone I think it is a good thing to have some kind of terms how to use the logo of an Open Source Project. It makes things a little easier. You could eg. grant the usage generally a specific context: in articles or books about Hugo (what you call fair use).
Personally, nevertheless, I would always ask the copyright holder (in this case @spf13) when I want to use a logo for example on a book cover or the frontpage of a brochure.