that's a fair and important question! Image rights are complicated and it's virtually impossible to foresee any problems that may arise. However, here is some reassuring background information on the matter:
a) In several places, including our Terms of Service, we state that it's the sole responsibility of the uploader to make sure no copyrights and related rights are violated by contributing images to Pixabay. Thus, the uploader should/will be held responsible in the case of a copyright infringement.
b) Usually, in such a scenario, you would forward the complaint/litigation/dissuasion to us, Pixabay. We would then do our best to mitigate and find a viable solution with minimum damage for all parties.
c) Upon upload, we manually check and approve each image concerning both, quality and suitability for the public domain. With our best knowledge, we try to filter out all problematic material. However, naturally there is no 100% guaranty. It's simply not possible!
d) Upon complaint ("Report image"), we react by removing concerned images from Pixabay immediately! This also improves safety for you; our users that is.
... e) We're already planning on some sort of insurance for such cases. It's a work in progress and the outcome is yet unclear. Nonetheless, I guess you see, we're putting a lot of thoughts and effort into this field, and I believe Pixabay is the safest place for public domain images across the globe .