Research-checked Last researched: 30 October 2026
iOS security updates, without the jargon
By the iphonefix.us editorial team · Research-based, last researched 30 October 2026.
Every few weeks your iPhone offers an update, and the description is usually one vague line about security. It is easy to tap Later and forget about it. Here is why that habit matters, and why two iPhones on two different iOS versions are not equally safe even if they look identical.
What a security update actually fixes
iOS is millions of lines of code, and researchers keep finding flaws in it — a flaw in the browser engine, in Bluetooth, in the way the phone handles a message. When Apple patches one, the update closes that specific hole. Before the update, anyone who knows about the flaw can potentially use it; after the update, that particular route is closed. Delaying an update does not keep you neutral. It keeps a known hole open.
How to update, safely
Back up first — iCloud Backup or a computer backup, either will do. Then Settings, General, Software Update, and install. If the phone is very old and storage is tight, free some space first rather than skipping the update entirely; an update that cannot download is the same as an update you ignored.
Software bugs vs checkm8: the key difference
Most iOS flaws are software flaws. Apple finds them, writes a patch, and the next update removes them. Checkm8 is different. It is a flaw in the bootrom — the very first code the chip runs when the phone powers on — in A11 chips and older (iPhone X and earlier). Because it is in hardware, not in iOS, no software update can erase it. That is why checkra1n and palera1n still work on those old devices years later, and why no update will ever make an iPhone X “unjailbreakable” in the same way.
Why version numbers matter for tools
This is also why tool compatibility is always stated as a device plus a version, never just a version. A tool that works on iOS 15 on an iPhone 8 may do nothing on iOS 15 on an iPhone 13, because the chips are different and the flaws are different. Any guide or vendor that talks about iOS versions without naming the chip or model is leaving out the half that decides whether it works.
When your phone stops getting updates
Eventually Apple drops a model from new iOS versions. The phone keeps working, but new flaws found after that point are not patched for it. That does not mean you must throw it away tomorrow, but it does mean you should not use it as your only device for banking, work email, or anything sensitive. For a spare phone, a music player, or a test device, an old unpatched iPhone is fine. For your main life, it is a risk that grows quietly.
Frequently asked questions
Should I always install an iOS update immediately?
For a security update, yes in most cases — that is the point of it. Back up first, then update from Settings, General, Software Update. Waiting leaves a known vulnerability open on purpose.
Why do old iPhones stop getting updates?
Apple supports each model for a number of years, then stops. After that, new vulnerabilities in that iOS version are no longer patched for that model, which is a real reason to consider a newer device for sensitive use.
What is the difference between a software bug and checkm8?
A software bug lives in iOS code and can be patched by an update. Checkm8 lives in the bootrom hardware of A11 and older chips, so no software update can fully remove it — which is why those old devices can still be jailbroken years later.
Related: palera1n and checkm8 devices · iOS compatibility map