GNU IceCat is based on the Mozilla Firefox source code. While the
basic Mozilla Firefox source code is free software, and we thank them
for their significant contributions to the community, some non-free
files are distributed in the Firefox source tree, and Firefox can
recommend non-free plugins. IceCat is entirely Free Software.

In addition, CAcert.org, already used for https://savannah.gnu.org, was
added to the builtin root certificates.