Sprint‘s (NYSE:S) Virgin Mobile USA users are vulnerable to a significant security flaw that could allow others to illicitly gain access to their accounts and view personal information.

The warning comes from computer expert Kevin Burke, who notes that the wireless service’s log-in service features only a six-digit password,

Fox News notes.

With passwords that small, there are only one million possible alphanumerical combinations available. Hackers can easily created programs that will run through all the possible passwords inside a day, eventually hitting the right one and gaining access to the account.

Burke claims he used a similar program to hack into his own account. All the hacker needs is a phone number to start the process.

Once an account has been compromised, unauthorized users can change the password, shutting the owner out his or her account, alter billing methods, and learn the actual user’s email address and physical address, as well as seeing the user’s call record and credit card information.

According to Burke, he advised Virgin Mobile of the security flaw last month, but the company failed to implement changes. He hopes that making the flaw public will compel the company to change its log-in process.

Shares of Sprint rose fractionally in Wednesday morning trading.