"The macOS Mojave 10.14.6 update improves the stability and reliability of your Mac, and is recommended for all users. This update:

Makes downloaded issues available in the My Magazines section of Apple News+, both online and offline.

Adds all publications in Apple News+, including newspapers, to the catalog at the top of the News+ feed.

Adds the ability to clear downloaded magazine issues in Apple News+ by selecting History > Clear > Clear All.

Addresses an issue which prevents creation of a new Boot Camp partition on iMac and Mac mini with Fusion Drive.

Resolves an issue that may cause a hang during a restart.

Resolves a graphics issue that may occur when waking from sleep.

Fixes an issue that may cause fullscreen video to appear black on Mac mini.

Improves file sharing reliability over SMB.

Enterprise content:

Addresses an issue where file-sharing connections would potentially drop.

Improves compatibility of Xsan clients when accessing volumes that use 1K or larger LUN sector sizes."

The 10.14.6 update includes Safari 12.1.2, available for 10.13.6/10.12.6 via software update.
(See below for docs on security fixes in 10.14.6, Security Update 2019-004 and Safari 12.1.2.)

Downloads of the Updates:
(Update: The 10.14.6 Updates revised again on Sept. 26th to include Supplemental update 2.
Also Apple pulled Security Update 2019-004, then reissued it July 29th.)

Apple revised 10.14.6 downloads below - pages now dated Sept. 26th


• Download macOS Mojave 10.14.6 Update (2.67GB)
  
  
• Download macOS Mojave 10.14.6 Combo Update (3.37GB)
  
  Apple revised downloads below for Security Updates 2019-005 on Sept. 26th
  
  
• Download Security Update 2019-005 (High Sierra) (1.9 GB)
  
  
• Download Security Update 2019-005 (Sierra) (938.1 MB)

• About the security content of macOS Mojave 10.14.6, Security Update 2019-004 High Sierra, Security Update 2019-004 Sierra (CUPS CVE-2019-8675/CVE-2019-8696 entry added 8/14. Bluetooth CVE-2019-9506 entry added 8/13.)
  
  
• About the security content of Safari 12.1.2
  "Available for macOS Sierra 10.12.6, macOS High Sierra 10.13.6, and included in macOS Mojave 10.14.6"
  
  
• What's new in the updates for macOS Mojave (added 10.14.6 info)

(Again Apple released macOS and iOS/tvOS/watchOS updates simultaneously so servers may be swamped initially.)

FYI: the original (July 22nd) Security Update 2019-004 caused kernel panics after wake from sleep for many users. (Some said the problem affected T1 and T2 chip Macs.) Apple pulled Security Update 2019-004 for both OS's and rereleased it July 29th. (Initial reports on the revised update seem positive from those that had problems with the original release.)

Reminder to Users of Nvidia Web Drivers:
(There's been no Mojave Nvidia web driver updates yet, but a reminder to 10.13.6/10.12.6 users of Nvidia's web graphics drivers.) New OS updates or later build numbers after Security Updates typically break currently installed Nvidia web graphics drivers. I'd switch to the default Apple driver and reboot before updating, if your card is supported with the default drivers. If not, wait for a Nvidia driver update. (Some non-Mac EFI cards are not supported by default OS X drivers.)
Nvidia Driver Updates of July 30th/31st, 2019 (Security Update 2019-004 builds):
These driver updates were for Security Update 2019-004 (NOT -005).
Info/Downloads of Nvidia Web Graphics Driver Updates for macOS 10.13.6 and macOS 10.12.6.
(These are driver updates for the July 29th rerelease of Security Update 2019-004 builds.)

• iOS 10.3.4 release notes
  (for iPhone 5, iPad (4th generation) Wi-Fi + Cellular)
  "iOS 10.3.4 addresses an issue that could impact GPS location performance and could cause system date and time to be incorrect. This update is recommended for all users."
  
  
• iOS 9.3.6 release notes
  (for iPhone 4s, iPad mini (1st generation) Wi-Fi + Cellular, iPad 2 Wi-Fi + Cellular, iPad (3rd generation) Wi-Fi + Cellular)
  "iOS 9.3.6 addresses an issue that could impact GPS location performance and could cause system date and time to be incorrect."
  
  
• iOS 12.4 release notes and security fixes.
  
  
• tvOS 12.4 release notes and security fixes.
  - "This update includes general performance and stability improvements."
  
  
• watchOS 5.3 release notes and security fixes.
  - Provides important security updates including a fix for the Walkie-Talkie app.
  - ECG app on Apple Watch Series 4 now available in Canada and Singapore.
  - Irregular heart rhythm notifications now available in Canada and Singapore.
  
  
• Apple TV (3rd generation) Software Update 7.3.1
  - "This update includes general performance and stability improvements."