Firefox 43.0.2 was released on December 22, with no announcement at all. I learned about the new version when my copy of Firefox offered to update itself. The release notes say only that the new version includes a new security certificate for Windows. The notes also mention “Various stability and security fixes”, but the linked Security Advisories page lists security fixes for all of Firefox 43. Presumably at least one security issue was fixed in 43.0.2, but it’s not clear.