Is there a fix for checkm8?

Apple didn’t allow anything to continue, the flaw was just discovered.

It does not work on any devices recently released after the X, XS and 11 aren’t affected.

According to security researchers:

• Checkm8 requires physical access to the phone. It can't be remotely executed, even if combined with other exploits
• The exploit allows only tethered jailbreaks, meaning it lacks persistence. The exploit must be run each time an iDevice boots.
• Checkm8 doesn't bypass the protections offered by the Secure Enclave and Touch ID.
• All of the above means people will be able to use Checkm8 to install malware only under very limited circumstances. The above also means that Checkm8 is unlikely to make it easier for people who find, steal or confiscate a vulnerable iPhone, but don't have the unlock PIN, to access the data stored on it.

https://arstechnica.com/information-technology/2019/09/developer-of-checkm8-explains-why-idevice-jailbreak-exploit-is-a-game-changer/?utm_source=fark&utm_medium=website&utm_content=link&ICID=ref_fark

Your mistaken it’s technically not a jailbreak although it could turn into one. Checkm8 is a hardware vulnerability in the read-only bootrom that was exploited; it compromises millions of iPhone’s from the iPhone 4s to the iPhoneX that cannot be patched by apple short from recalling phones under warranty.

The newer iPhones after the IPhoneX do not have this vulnerability meaning it was patched via new hardware and apple know’s about the issue, but decided not to publicly acknowledge it.

It’s tethered meaning in and of itself isn’t great for a jailbreak because it requires physical access and undoes itself upon reboot requiring the exploit to be initialized again to the device using USB, but it can allow someone to downgrade the phone to a less secure iOS version, install malware, install a tethered jailbreak, install a modified iOS firmware, install iCloud lock bypasses, and dump the secure rom which may possibly allow the encryption to be bruteforced on devices like the iPhone 4s & 5c that do not have Secure Enclave’s. All of the above have caveats but that’s what iOS security researchers are working on.

Help me understand why you are concerned about this? YOU would have to do this to your phone yourself. Are you planning to do this? If you aren't planning to do this, it can't happen by itself. And if someone wants to do this and bricks their phone, Apple won't help them at all.

To quote an expert on this subject: The exploit is certainly a big deal for the jailbreak community, apart from that it makes no difference to nearly every iPhone or iPad user outside of that community.

So I'm not sure what it is you're accusing Apple of here or why it's concerning to you?

Correct. That is currently what we know so far. Although their have been talks of ways to allow a semi-tether by chaining it with other exploits to allow persistence at some level eventually, but only time will tell if this happens or not and does not change the fact it would require physical access to the device.

Unauthorized modification of iOS can cause security vulnerabilities, instability, shortened battery life, and other issues - Apple Support

Don't jailbreak your phone. If you don't jailbreak it, there is nothing to be 'fixed' on your phone.