Updated at 10 p.m. PT with comments from Google.
A researcher has found that Google's JotSpot service, which allows people to collaborate on online documents, exposes user names and e-mail addresses to anyone on the Internet, but Google says the problem is due to administrator users not making the settings private.
As a result, sensitive user data is indexed by Google's crawler and made accessible on the Web, said Ben Edelman, a Harvard Business School professor and security researcher.
"This is not a security issue," a Google spokesman said in an e-mail. "The information in these wikis is accessible because they have been set to public on the Site Permissions page. Users are always in control of the information they share. If wikis are set to private, no information will be publicly accessible."
JotSpot Wikis are private by default and no information is made public unless the group administrator changes the privacy controls, the Google spokesman said.
CNET News was able to view full user names, e-mail addresses, and group memberships of JotSpot users. This was done by searching Google for "user management" pages on JotSpot that list registered users for different JotSpot projects or groups. Such a search conducted late on Thursday brought up about 2,800 results.
Each user listed on the user management pages has a link to a page with more information, including an e-mail address.
This was the case even for wiki pages that groups designated specifically as being private, Edelman wrote in a blog post. A test of one of Edelman's examples showed that the user management page for a private group was no longer accessible, so Google may have removed public access to some of those pages.
Edelman said he notified Google of the security problems a week ago and that some of the affected sites were modified to address the situation Monday.
The security lapse not only exposes data that users believed was protected, but it puts the users at risk of being spammed and of being victimized by a social engineering attack, Edelman said.
Told of Google's comment, Edelman said that even if the problem is due to users not setting the privacy settings adequately, the matter still reflects poorly on Google.
Google acquired JotSpot two years ago.
The problem also exposes a chink in Google's hosted services business, which relies on customers--individuals and companies--having faith in Google's ability to secure customer data, he said.
"JotSpot's postings are, by all indications, accidental. But in the context of a series of similar slip-ups, this error raises questions about the efficacy of Google's model of hosted applications," Edelman wrote.
Edelman mentions three Gmail-related security weaknesses since January 2007 that exposed full user names, allowed Web sits to retrieve user contact lists and to forward e-mails to attackers from Gmail accounts.
"As these services become increasingly widely used, each slip-up exposes an ever-larger amount of data," he writes. "So far few users seem concerned, but I suspect these hidden challenges will ultimately impede the server-based applications Google envisions."