A security flaw in the Google Docs software meant that the documents of some users were flagged as collaborative items, allowing third party users of the service to access - and amend - the files.
In a blog posting, Google said that a small number of users were affected by the issue.
"The inadvertent sharing was limited to people with whom the document owner, or a collaborator with sharing rights, had previously shared a document," says the blog posting.
Curiously, Infosecurity understands that the bug did not affect all the editing features of Google Docs.
Whilst text documents ad presentations could be accessed by third parties, spreadsheet files were not accessible.
Google says it is contacting all the affected users and warning that their files may have been compromised.
The company says that around 0.5% of its registered users were potentially affected by the bug.
In a a prepared statement to users, Jennifer Mazzon, Google's product manager for the Google Docs service, said that, as part of the fix, the company used an automated process to remove collaborators and viewers from the documents that we identified as having been affected.
"We then emailed the document owners to point them to their affected documents in case they need to re-share them."
"We're sorry for the trouble this has caused. We understand our users' concerns (in fact, we were affected by this bug ourselves) and we're treating this very seriously. We hope this explanation provides greater clarity."