Over the weekend, the Associated Press reported on an unusual AT&T network glitch that gave some mobile users the ability to login to other people’s Facebook accounts. While the problem only affected a small handful of users, the story reveals the tenuous technological grip we rely on to protect our digital identities and private information.

From the report:

Candace Sawyer, 26, says she immediately suspected something was wrong when she tried to visit her Facebook page Saturday morning.

After typing Facebook.com into her Nokia smart phone, she was taken into the site without being asked for her user name or password. She was in an account that didn’t look like hers. She had fewer friend requests than she remembered. Then she found a picture of the page’s owner.

“He’s white — I’m not,” she said with a laugh.

Sawyer logged off and asked her sister, Mari, 31, her partner in a dessert catering company, and their mother, Fran, 57, to see whether they had the same problem on their phones.

Mari landed inside another woman’s page.

Fran’s phone — which had never been used to access Facebook before — took her inside yet another stranger’s page, one belonging to a young woman from Indiana. They sent an e-mail to one of their own accounts to prove it.

They were dumbfounded.

“I thought it was the phone — ‘Maybe this phone is just weird and does magical, horrible things and I have to get rid of it,’” said Candace Sawyer.

The women, who live together in East Point, Ga., outside Atlanta, had recently upgraded to the same model of phone and all used the same carrier, AT&T.

According to a follow-up report from ReadWriteWeb, AT&T and Facebook have worked quickly to determine what caused the glitch and have already set about fixing it.

From the RWW report:

As it turns out, those affected were logging into Facebook using their AT&T phone numbers as opposed to a username/password combination. Typically, when a username and password is used, a cookie is stored on the mobile device. This small file retains a user’s login credentials, allowing them to access Facebook without having to re-enter their sign in information. When a cookie is not available, the subscriber information is sent to Facebook.com automatically. This is what had taken place in the reported incidents.

[...]

AT&T reports that they’ve now put additional “security measures” in place to prevent a reoccurrence of this issue but won’t elaborate on what precisely those measures involve. In addition, the wireless company states they are working with Facebook to disable the use of subscriber information as a method for automatic login. That means going forward, AT&T users will no longer be able to use their phone numbers as login credentials to access Facebook from their mobile devices. Only a username and password combination will be allowed.

Because this glitch was a very isolated incident, AT&T users shouldn’t be worried that strangers around the country are logging into their Facebook accounts. However, it does show how technology is not infallible. On the web, there is very thin line separating our public and private lives, and it doesn’t take much for one side to cross to another.