A bug in photo-sharing site Flickr made some users' private photos publicly visible for nearly a month.

An email Flickr sent to affected users, including a writer at Marketing Land, noted that certain private photos were visible to the public for a 20-day period ending last week.

Flickr said the photos were only visible via direct links. The images did not appear in Flickr search, nor were they indexed by Google or other search engines.

Flickr was not able to tell Marketing Land's Barry Schwartz whether his apparently private images had been viewed by someone else. However, one commenter on the Flickr forums pointed out that users might be able to tell whether others saw their private photos by checking their statistics pages.

For those affected, Flickr took the extra step of changing the settings on any potentially impacted photos to private, meaning that links and embeds of photos that were previously public and had been switched to private would no longer work.

That upset some users, including Veterok, who claimed to have carefully adjusted privacy settings on uploads since joining Flickr in 2006.

First I was annoyed about around 10 of my friends only pictures (many with my contact details) turn public, but now I'm much more pissed off about Flickr's decision to randomly turn my public pictures private so that I must comb though EVERY picture to see whether they are private, public or friends only and what to do about them.

Jim Frazier added that the descriptions on affected photos also appeared to have vanished.

The issue may be more problematic for those with racier photos on their Flickr accounts. Flickr user kathynails1 noted that she had "naughty photos and they are for friends only."

Flickr vice president Brett Wayn said a small percentage of people were affected and the bug only changed the settings on photos uploaded between April and December of last year. He added that, "This is not a widespread nor an ongoing issue -- the software bug has been identified and fixed."

Flickr's hardly the only major Web community to suffer from privacy issues. Facebook has had its troubles in that department, with the recently-added Graph Search feature unearthing details people may not want to be public knowledge about themselves.

Photo by poolie/Flickr