877-208-8801

If it was CIBC they'd mention what I owed them.

If it's legit, then they don't need your information because the number you called from is registered with them.  Call block doesn't block when calling this number.

IT IS NOT CIBC!!!!!!!!!!!!!!!!  Since when did CIBC not identify themselves when calling, or lock your cards...or, if you don't select the right option when asked for ages of people in the house when asked,  which I did on purpose, the recording says the number has changed and it tries to re-direct..very amateur scammer....

CIBC fraud Alert number is 1-800-267-5193 (just checked again on their web site), don't know about 1-877-208-8801

I received a call from this number about fraud prevention relating to recent global money transfers I made. I did make these transfers, so the timing was appropriate. They asked for my debit number, but otherwise it seemed trustworthy.

With a little digging I have found evidence that the number is official and is operated by CIBC. See here, their official twitter account mentions it, and also addresses a reply in which they are asked if it is legit:
twitter.com/cibc/status/935971893533990912

That is the cibc banking security phone number.

Did they also happen to mention that scammers frequently spoof legitimate phone numbers so you should never trust a random caller to be who they claim and that you should never give personal information to such a caller?

FRAUD CALL CIBC