Apple has made it prohibitive to jailbreak iOS, which allows you to install whatever software you want on the usually locked-down devices. But on Saturday, the Unc0ver jail-breaking team released a tool that will jail-break all iOS versions from 11 to 13.5.

Unc0ver says its jailbreak, which can be activated using AltStore and Cydia 's long-term jailbreaking tools, is secure and does not drain battery life or prohibit Apple apps such as iCloud, Apple Pay or iMessage from being used. And the community argues that it maintains data privacy for Apple users and does not compromise the security of the iOS sandbox, which keeps programs running separately so they can't access data they shouldn't.

"This jailbreak essentially just introduces exceptions to the current rules," the lead developer of Unc0ver, who goes by Pwn20wnd, told WIRED. "It just helps you to read new jailbreak files and filesystem sections that don't contain user data."

Early public reactions to the jailbreak suggest that it works as expected, including from researchers who tested it before its publication. But the group has not yet had time to thoroughly evaluate the arguments of the jailbreak or Unc0ver regarding its security safeguards. And the method is not open source, meaning that it would be harder to study.

iOS's jail-breaking heyday effectively ended with the introduction of iOS 9 in 2015; that's when Apple launched a new kernel protection feature called Rootless and other iOS safeguard initiatives. Yet the group began storming back in the last year. Apple mistakenly reintroduced a previously patched bug in iOS 12.4 in August that gave enthusiasts a few days of jailbreaking before the fix was reset. A researcher then published details of an unpatchable Apple hardware flaw in September that could be exploited to jailbreak virtually any type of Apple mobile device released between 2011 and 2017, including iPhones , iPads, Apple Watches, Apple TV's. The release, known as checkm8, marked a turning point, as it provided unparalleled open access to a wide population of Apple mobile devices. But checkm8 hasn't spread to Apple devices launched after 2017.

Today's Unc0ver jailbreak is the first in years to be built on a so-called zero day vulnerability. This means that Unc0ver has not announced its results to Apple beforehand, and that there will be no patch arriving in the next few days that will stop the jailbreak. The error is in the kernel of iOS, the software at the very heart of an operating system. Both Pwn20wnd and independent iOS security researchers predict that it will take Apple to prepare a fix for a minimum of two to three weeks, unless they have discovered the bug independently and are patching it. Apple did not return a WIRED request for comment.

"I'm just personally excited to see a no-bullshit jailbreak dropped for the latest iOS," says Will Strafach, a longstanding iOS jailbreaker and the guardian firewall app creator for iOS. "It is really in line with the spirit of the early jailbreak."

While attackers may use jailbreaking to compromise devices as it often opens the door to more types of malware being installed, the research community generally supports the practice. Jailbreaks make it easier to remove restrictive protections from Apple, analyze how iOS conducts, and prove potential weaknesses and flaws. Security researchers focused on Apple and iOS have been caught up in an increasingly heated battle over the tradeoffs of Apple's stringent security defenses. Researcher says these defenses can make fundamental security assessments — like whether malware has compromised an iOS device — harder to execute. Last year, Apple sued security company Corellium for creating an iOS emulator that researchers could use to test the operating system.