Checkm8 Exploit Opens Door to Unpatchable Jailbreak on iPhone 4S Through iPhone X

A security researcher who goes by "axi0mX" on Twitter today released "checkm8," which he claims is a bootrom exploit for iOS devices equipped with A5 through A11 chips, including the iPhone 4S through iPhone X, several iPad models dating back to the iPad 2, and the fifth-generation iPod touch and later.

trio iphones ios
This would be the first publicly released bootrom exploit since the iPhone 4 in 2010 and pave the way for a permanent, non-patchable jailbreak on hundreds of millions of affected iOS devices. Since the bootrom is read-only, Apple cannot patch this type of exploit with a software update.


The bootrom exploit has many other possibilities on affected devices, including downgrading iOS versions without SHSH blobs or APTickets, dual booting iOS, and running custom firmwares, according to jailbreak enthusiasts.

This is significant news in the jailbreaking community, as the last bootrom exploit known as "limera1n" was released by George "geohot" Hotz nearly a decade ago for devices with A4 chips and earlier, including the iPhone 4, iPhone 3GS, the third- and fourth-generation iPod touch, and the original iPad.

Popular Stories

Generic iOS 19 Feature Mock Light

iOS 19 Leak Reveals All-New Design

Friday January 17, 2025 2:42 pm PST by
iOS 19 is still around six months away from being announced, but a new leak has allegedly revealed a completely redesigned Camera app. Based on footage it obtained, YouTube channel Front Page Tech shared a video showing what the new Camera app will apparently look like, with the key change being translucent menus for camera controls. Overall, the design of these menus looks similar to...
2024 iPhone Boxes Feature

Apple Changes Trade-In Values for iPhones, iPads, Macs, and More

Thursday January 16, 2025 6:45 am PST by
Apple today adjusted estimated trade-in values for select iPhone, iPad, Mac, and Apple Watch models in the U.S., according to its website. Some values increased, while others decreased. The changes were not too significant, with most values rising or dropping by $5 to $50. We have outlined some examples below: Device New Value Old Value iPhone 15 Pro Max Up to $630 U ...
2024 App Store Awards

Apple Explains Why It Removed TikTok From the App Store in the U.S.

Sunday January 19, 2025 6:58 am PST by
Apple on late Saturday removed TikTok from the App Store in the U.S., and it has now explained why it was required to take this action. Last year, the U.S. passed a law that required Chinese company ByteDance to divest its ownership of TikTok due to potential national security risks, or else the platform would be banned. That law went into effect today, and companies like Apple and Google...
Generic iOS 18

Everything New in iOS 18.3 Beta 3

Thursday January 16, 2025 12:39 pm PST by
Apple provided the third beta of iOS 18.3 to developers today, and while the betas have so far been light on new features, the third beta makes some major changes to Notification Summaries and also tweaks a few other features. Notification Summary Changes Apple made multiple changes to Notification Summaries in response to complaints about inaccurate summaries of news headlines. For...
iOS 19 Roundup Feature

iOS 19 Rumored to Be Compatible With These iPhones

Saturday January 18, 2025 10:28 am PST by
iOS 19 will not drop support for any iPhone models, according to French website iPhoneSoft.fr. The report cited a source who said iOS 19 will be compatible with any iPhone that can run iOS 18, which would mean the following models: iPhone 16 iPhone 16 Plus iPhone 16 Pro iPhone 16 Pro Max iPhone 15 iPhone 15 Plus iPhone 15 Pro iPhone 15 Pro Max iPhone 14 iPhon...
iPad Pro vs iPhone 17 Air Feature

Here's How Thin the iPhone 17 Air Might Be

Friday January 17, 2025 3:38 pm PST by
For the last several months, we've been hearing rumors about a redesigned version of the iPhone 17 that Apple might call the iPhone 17 "Air," or something along those lines. It's going to replace the iPhone 17 Plus as Apple's fourth iPhone option, and it will be offered alongside the iPhone 17, iPhone 17 Pro, and iPhone 17 Pro Max. We know the iPhone 17 Air is going to be super slim, but...
airtag 4 pack blue

AirTag 2 Launching This Year With These 3 New Features

Sunday January 19, 2025 8:11 am PST by
After a four-year wait, a new AirTag is finally expected to launch in 2025. Below, we recap rumored upgrades for the accessory. A few months ago, Bloomberg's Mark Gurman said Apple was aiming to release the AirTag 2 around the middle of 2025. While he did not offer a more specific timeframe, that means the AirTag 2 could be announced by the end of June. The original AirTag was announced...
apple power beats pro 2

Powerbeats Pro 2 Coming Soon: Apple to Announce Them 'Imminently'

Sunday January 19, 2025 8:25 am PST by
In September, Apple said that it would be launching Powerbeats Pro 2 in 2025, and it appears the wireless earbuds are coming very soon. Powerbeats Pro 2 images found in iOS 18 code In his Power On newsletter today, Bloomberg's Mark Gurman said the Powerbeats Pro 2 are "due imminently." In addition to Apple filing the Powerbeats Pro 2 in regulatory databases last month, Gurman said Apple is...

Top Rated Comments

zorinlynx Avatar
70 months ago

This can't be good for the security of these devices...

And have malware installed or spying on you. No thanks. Apple should have gotten their sh** together and not have had the exploit open for nearly a week.
This is a bootrom exploit. It can only be exploited when the device is in DFU recovery mode and will not affect the security of devices being used normally.

This is really the best kind of jailbreak exploit because only the people who really want to go out of their way to jailbreak can use it. Regular users are safe; all it means is that people can do whatever they like with these devices they own now.
Score: 35 Votes (Like | Disagree)
itsmilo Avatar
70 months ago

All the cool kids violate their warranty. Didn't you know?
one restore on iTunes and your warranty is „restored“ so to speak
Score: 28 Votes (Like | Disagree)
tobefirst ⚽️ Avatar
70 months ago
I haaaaaaate the new force press/haptic touch menu on iOS 13. I would consider jail breaking just to go back to how that worked on my X on iOS 12.
Score: 16 Votes (Like | Disagree)
Jeremy1026 Avatar
70 months ago
I haven't been jailbroken since the 3G, what's the big draw of a jailbreak now a days?
Score: 15 Votes (Like | Disagree)
redheeler Avatar
70 months ago
Good, now we can have proper downgrade rights on these devices. It's sad that something like this is needed to, for example, downgrade to iOS 10 on an iPad Air 2 for the simple purpose of running 32-bit apps.
Score: 14 Votes (Like | Disagree)
Krevnik Avatar
70 months ago

Once the data is copied off the phone can't you brute force it without fear of being locked out? What's the encryption like?
You can read through the details yourself if you want: https://www.apple.com/business/docs/site/iOS_Security_Guide.pdf

The NAND itself is encrypted with AES 256. The passcode is the weak point, but to generate the AES 256 key from the passcode, you need the passcode and the unique AES 256 key burned into the Secure Enclave on the SOC. The passcode is run through PBKDF2 and then tangled with the AES 256 key in a one-way operation.

So dumping the flash raw means you face AES 256 at full strength, even if you know the passcode, because you also need the AES 256 key from the SOC to be able to recreate the key yourself if you aren't just brute forcing AES.

The fastest way to crack an iPhone is to brute force the passcode and bypass the lockout on attempts if you can. It also gives you the most access to the content.

Individual containers/files can be encrypted with separate keys based on the level of access the OS should have in different states of lock/unlock, on top of the NAND encryption. So if you dump the flash unencrypted, you then also need to crack the containers for things like email and messages which are also AES 256 encryption. All the more reason to focus even more on the passcode and attempt lockout mechanisms.


This is a bootROM exploit. Every iPhone ever manufactured excluding the iPhone XS and 11 series will always be vulnerable to this exploit regardless of any iOS updates. There is no patch.
Apple still manufactures the iPhone 8 and 3rd Gen Air. I wouldn't be surprised if we see manufacturing runs of those that include the patched boot ROM.
Score: 14 Votes (Like | Disagree)