Shared links

Researchers found that Dropbox's shared links to supposedly private documents could leak to third parties — exposed through browser referer headers and, in some cases, surfacing in Google search results — revealing tax returns, bank records, and business plans.

A viral 2014 incident revealed that Dropbox compares the cryptographic hashes of files users try to share against a blacklist of DMCA-flagged content and blocks matches — surprising users who assumed their files were entirely private.