Direct download URLs for Safari versions released on 2017-01-23.
Safari 10.0.3 for macOS 10.10 Yosemite:
http://swcdn.apple.com/content/downloads/14/51/031-94352/wlp1v4omq45sda5f96h4ejdfeg4nw71uoa/Safari10.0.3Yosemite.pkg
Safari 10.0.3 for macOS 10.11 El Capitan:
http://swcdn.apple.com/content/downloads/12/57/031-94947/cr24vq2drkmwz8fqvy4cocqs4lo2sgbujw/Safari10.0.3ElCapitan.pkg
Safari 10.0.3 for macOS 10.12 Sierra is included with the 10.12.3 update. URL to combo DMG file on Apple’s support site is below:
http://support.apple.com/downloads/DL1905/en_US/macosupdcombo10.12.3.dmg
