I was also able to fix this issue by upgrading libnss3:
Package: firefox (amd64)
Version: 48.0-2
$ sudo apt install libnss3=2:3.26-1
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
libnss3-1d
The following packages will be upgraded:
libnss3
1 upgraded, 0 newly installed, 1 to remove and 1 not upgraded.
Need to get 1,158 kB of archives.
After this operation, 46.1 kB disk space will be freed.
Do you want to continue? [Y/n]
Get:1 http://ftp.us.debian.org/debian unstable/main amd64 libnss3 amd64
2:3.26-1 [1,158 kB]
Fetched 1,158 kB in 0s (2,444 kB/s)
Retrieving bug reports... Done
Parsing Found/Fixed information... Done
Reading changelogs... Done
(Reading database ... 292437 files and directories currently installed.)
Removing libnss3-1d:amd64 (2:3.25-1) ...
(Reading database ... 292430 files and directories currently installed.)
Preparing to unpack .../libnss3_2%3a3.26-1_amd64.deb ...
Unpacking libnss3:amd64 (2:3.26-1) over (2:3.25-1) ...
Setting up libnss3:amd64 (2:3.26-1) ...
Processing triggers for libc-bin (2.23-5) ...
