Verizon Wireless acknowledged this week that customers who signed up to the company's online billing service were able to access the records of other customers simply by inputting a different telephone number. The glitch was attributed to a programming error, which has now been corrected.

Unlike other recent data leaks that have prompted identity theft concerns, Verizon said customers could only view limited details of other accounts. The exposed data included minutes used and free minutes remaining, as well as the phone make and model used by that customer.

But developer Jonathan Zdziarski, who discovered the problem, said account balances and the date of the customer's most recent payment were also displayed to anyone taking advantage of the Web site glitch. Zdziarski stumbled upon the issue while writing a program to automatically access his account.

Verizon did not verify Zdziarski's claim, but admitted the problem could have existed for as long as five years and affected all customers registered with the system. However, the company said it did not appear anyone had accessed accounts using the hole.

"Sensitive information," such as records of calls placed and social security numbers, were not leaked due to the flaw Verizon officials said.