Apple’s latest beta includes a patch for an exploit that the Evasi0n iOS 7 jailbreak took advantage of.
iOS 7.1 beta 5 includes a fix for the “chown” and “afc sandbox escape,” which Evasi0n exploited to jailbreak iOS devices.
Still, as App Advice says, jailbreaking is a constant cat and mouse game with Apple. One hole is patched and the team of iPhone hackers finds another. Sometimes, they find several in hopes of being prepared for when Apple closes one.
Don’t download iOS 7.1 if you’re using a jailbroken device.