[worldofmatthew]

This should not be news to anyone. Facebook scans all links posted in Messenger.

[sushid]

This is links INSIDE a pdf. Thats one step further than most people assumed.

[manojlds]

Mostly to scan the PDF and ensure it's safe I believe, or atleast that's would be the stated reason.

[strstr]

I can believe that (despite the obvious creepyness), since FB users have a knack for getting owned and spreading that ownage to other users.

[gryffin]

PDF is an open format. Scanning PDF for the links is probably the least you could assume.

You gotta assume they will reconstruct generations of your family tree if they can from your chat history.

[twothamendment]

"...reconstruct generations of your family tree if they can from your chat history."

People might pay good money for that!

[nitwit005]

Then people have strange assumptions.

Once a service starts blocking malicious links, the obvious next step is to conceal the link through some sort of indirection.

[joshspankit]

I would also assume they are scanning links in zip files and (if anyone is crazy enough to do this) links visible in images

[axegon_]

This. I honestly don't get why this is news. I truly hate facebook with a passion, I really do. But on this occasion I don't really blame them: You know what you are getting yourself into, what did you expect? A tuna salad? You shouldn't really be sharing any personal information on any platform which you can't hold accountable, regardless of e2e encryption.