A small number of users were affected by a Flickr privacy bug that set private photos public.
Users were notified directly by Flickr in an email rather than publicly via blog post. The email said that private photos uploaded between April and December 2012 had accidentally been made public for a 20-day period spanning 18 January through 7 February 2013. It also stated:
While performing routine site maintenance, we identified a software bug that may have changed the view setting on some of your photos from non-public (ie, private or viewable only by family and friends) to public.
Flickr maintained that images were not surfaced through search, though anyone browsing photo streams may have seen images that were not meant to be public. Flickr has a few layers of photo privacy; "public" lets anyone see images, while "private" can be locked down to allow viewing by the uploader alone, or friends and family.
Many users have been discussing the privacy breach through threads in Flickr's forums, with several saying that the breach has made them consider leaving the photo-sharing service.