On a clean puppet4 installation with CFacter, facter -p runs fine.
When I run it against my existing puppet infrastructure, I get : 
2017-10-03 11:33:47.023229 WARN  puppetlabs.facter - Could not initialize locale, even with LC_* variables cleared. Continuing without localization support
2017-10-03 11:33:50.301838 FATAL puppetlabs.facter - unhandled exception: cxxrt::bad_alloc


Deleting all my custom facts, solves the issue. But then if I do:
export LC_CTYPE=en_US.UTF-8

and rerun facter -p, the command goes through and all my facts are reported correctly.
Running only facter executes correctly.

Attaching gdb with : 
(gdb) b 'std::bad_alloc::bad_alloc()'
Function "std::bad_alloc::bad_alloc()" not defined.
Make breakpoint pending on future shared library load? (y or [n]) n
(gdb) run -p
[New Thread 808216f00 (LWP 101455/ruby-timer-thr)]
2017-10-03 11:40:41.899334 FATAL puppetlabs.facter - unhandled exception: cxxrt::bad_alloc