Yes. Current stable did not have Firefox ESR 52 when current stable was released...

		kzrdude on Nov 12, 2017 \| parent \| context \| favorite \| on: Linux sandboxing improvements in Firefox 57 Yes. Current stable did not have Firefox ESR 52 when current stable was released, but it has it now. Debian is providing Firefox ESR 52 even in oldstable (check security upgrades) https://tracker.debian.org/pkg/firefox-esr