Update 2018-06-30

After updating Ubuntu packages gem v2.5.2 is working again!

The following packages were updated on running apt-get update && apt-get upgrade -y:

 cpp-5 g++-5 gcc-5 gcc-5-base libasan2 libatomic1 libcc1-0 libcilkrts5 libgcc-5-dev libgomp1 libitm1 liblsan0 libmpx0
  libquadmath0 libssl-dev libssl-doc libssl1.0.0 libstdc++-5-dev libstdc++6 libtsan0 libubsan0 openssl
  update-notifier-common

Yay!

My Original Post

I can't install anything with gem install bundler. Ruby barfs out this stack dump.

Reinstalled rbenv and tried both with installing Ruby v2.3.3 and v2.5.1. Both output the same error.