Debian has published security announcements for glibc [1] and eglibc [2]. Updates should be available from http://security.debian.org/ (and I was able to install them).

Also, keep this in mind:

>While it is only necessary to ensure that all processes are not using the old glibc/eglibc anymore, it is recommended to reboot the machines after applying the security upgrade.

[1] https://lists.debian.org/debian-security-announce/2016/msg00...

[2] https://lists.debian.org/debian-security-announce/2016/msg00...

As a brute-force fix, you can disable DNS in /etc/nsswitch.conf and put the addresses you need (at least security.debian.org, YOUR_MIRROR) in /etc/hosts.