See https://www.mozilla.org/en-US/firefox/52.5.2/releasenotes/ Fixes https://www.mozilla.org/en-US/security/advisories/mfsa2017-28/ (one windows-only, the other might affect other platforms) note that 52.5.1 was skipped upstream.
See https://www.mozilla.org/en-US/firefox/52.5.2/releasenotes/ Fixes https://www.mozilla.org/en-US/security/advisories/mfsa2017-28/ (one windows-only, the other might affect other platforms) note that 52.5.1 was skipped upstream.