I distinctly recall, c. 1983, that 'read' was called as part of the NFILE protocol.

The reason I noticed was that I had created a package that did not use 'lisp:', and therefore 'nil' was no longer 'lisp:nil', which broke the NFILE client.

Maybe this got fixed sometime between then and 8.3. (Or maybe NFILE was ripped out altogether?)

I also recall that Jeff Schiller found some remote vulnerabilities. I don't know if they involved 'read', but they certainly could have. Again, this was long before 8.3.

Are you sure? There is a READ command in NFILE, but there are no obvious calls to READ.

Symbols could have been created or looked up by other means...

I read it on a tweet somewhere.

Then it must be true.