ANY possible way a savvy thief can jailbreak/erase/reformat my stolen iPhone and somehow override Activation Lock?

The IMEI black list is held the by cell carriers. That's the only place to check whether its been blacklisted or not, which does not in itself tell you if its stolen or not. Just that it has been black listed. unless you specifically requested your carrier to black list it, it will not appear in that list.

If you enabled lost mode, then it locked down, and there is no currently known way of bypassing Activation lock.

The last time Activation lock was know to have been bypassed was in 2015, on an iPhone 5c, and the FBI had to pay a security company with lots of high end equipment over a million dollars to do it.

After that event, the vulnerability used was reported to Apple, and they promptly fixed the issue in a subsequent iOS update, and disabled it completely via hardware in newer phones.

Activation Lock is still regarded as one of if not the most secure mechanisms out there for a mobile device

Fionaussie wrote:

Thanks for taking the time to reply. If this is the case, why do people steal iPhones if they're going to be useless? Surely there's a way to wipe the phone and reformat so it can be used. I saw where this can be done using a "DNS" method (?) ...

Five years or so ago before Apple introduced Activation Lock it was easy for a thief to sell a working, used phone. All they needed to do was erase it and it was essentially like new. Apple then introduced Activation Lock (which is turned on by default by the way) which requires the owner (as defined by the Apple ID and password set on the device) to disable before the device can be reset by a person who is not the owner.

So some of this may be habit, plus there will always be some people who disable the Find My feature, basically making their phones as secure as they were pre-Activation Lock. In addition, if you routinely read posts here you will see half a dozen or more per day from people who have bought Activation Locked phones on E-bay or somewhere, so what does a thief care if they can sell somebody a phone that is useless to the buyer?

No way currently to wipe it if its locked and Find My iPhone is turned on.

Most people steal them thinking they can be used, and then simply sell them to unsuspecting customers when they realize they cannot be used. Others simply steal them to resell them, they don't really care whether they can actually be used.

So, no, as long as its locked, it cannot be wiped and reused. It may be resold, but no one will be able to actually use it.

Call your carrier if blacklisting is available.

There's nothing else a thief can do with it other than find some poor unsuspecting person who doesn't know about features such as Activation Lock who is willing to buy it from them.

Fionaussie wrote:

If this is the case, why do people steal iPhones if they're going to be useless?

People do not become petty thieves because they are super geniuses. And, there are always going to be people who believe prices that are too good to be true.