An anonymous reader quotes a report from Motherboard: The vulnerability was found and reported by a security researcher on December 19 of last year, but it hasn't been revealed until now. Within a day, T-Mobile classified it as "critical," patched the bug, and gave the researcher a $5,000 reward. That's good news, but it's unclear how long the site was vulnerable and whether any malicious hackers found and exploited the bug before it was fixed. The newly disclosed bug allowed hackers to log into T-Mobile's account website as any customer. "It's literally like logging into your account and then stepping away from the keyboard and letting the attacker sit down," Scott Helme, a security researcher who reviewed the bug report, told Motherboard in an online chat. Shortly after we published this story, a T-Mobile spokesperson sent us a statement: "This bug was confidentially reported through our Bug Bounty program in December and fixed within a matter of hours," the emailed statement read. "We found no evidence of customer information being compromised."