NEW YORK (CNNMoney)- Well, that was fast. Someone figured out how to hack Yo, the ridiculously popular messaging app that lets users send the word "Yo" to contacts.
What did the hackers take advantage of? Pretty much everything the app has to offer: They can spam users with custom messages and even spoof other users.
Or they could. The app's developer, Or Arbel, said that particular vulnerability had been fixed since he learned about it at 1 a.m. He had it fixed by business hours.
But Arbel admitted there are other vulnerabilities on the app that he created in just eight hours.
"Some of them have been fixed, and we're working on every one," Arbel said.
He declined to elaborate, saying he didn't want to give hackers too much information.
A widely publicized hack was shown in a Vine, where a user's phone plays Rick Astley's "Never Gonna Give You Up" instead of the app's standard "Yo" (which comes in the form of sound and text).
Arbel told CNNMoney he wasn't aware of the Vine hack. After watching the video, he claimed that hackers can do this to their own phones but can't do it to others' remotely.
The Yo app, which premiered in April, exploded in popularity this week. It made it into the top 10 most-downloaded free apps on the iTunes store days after it was revealed that it had raised $1 million in venture capital.
Arbel said the hacks had concerned users, but he maintained that there were no significant dangers.
Hackers, for instance, cannot access users' contacts because Yo doesn't store them on its servers.
"What's the worst that can happen?" Arbel asked. "They can Yo you."