The forks module of my Perl installation is causing a segfault and I can't run any script that uses it.

Did you install the module without successfully running the test suite?

You should run the test suite and send the report to the author, like cpan testers do :)

Send it maybe using cpant, or maybe using cpan command test_report (needs CPAN::Reporter )

Do you have any idea what might be wrong?

Its simple, you're using forks :) use threads, same API, probably no segfault :D

OTOH, I did read some stuff about COW related segfaults, and forks is all about fork which is all about COW, so if you're interested in searching visit https://rt.perl.org/, http://www.nntp.perl.org/group/perl.perl5.porters/ ...

Any ideas on how I can find out more about what's causing the segfault?

Debugging :) strace, gdb, http://blogs.perl.org/users/mithaldu/2014/05/segfault-fixing-for-dummies.html ... maybe its the way you write code that is causing the segfaults

Do the easy things first, examine the way you structured your code, try threads proper ... :)