For our customers' protection, Apple doesn't disclose, discuss, or confirm security issues until an investigation has occurred and patches or releases are available. Recent releases are listed on the Apple security updates page.
Apple security documents reference vulnerabilities by CVE-ID when possible.
Released October 4, 2017
watchOS 4.0.1 includes the security content of watchOS 4 and is available for Apple Watch Series 3 (GPS + Cellular).