macOS Big Sur 11.3.1 Update with Security Fixes Released

May 3, 2021 - 1 Comment

macOS Big Sur

Apple has released macOS Big Sur 11.3.1 update with an important security fix that is recommended for all macOS Big Sur users to install. The security patch update has arrived just a week after 11.3 debuted.

Separately, Apple also released iOS 14.5.1 and iPadOS 14.5.1 to address the same security issues for iPhone and iPad users, iOS 12.5.3 for older iPhone and iPad models, along with watchOS 7.4.1 for Apple Watch users.

How to Download MacOS Big Sur 11.3.1 Update

Be sure to backup the Mac with Time Machine before installing any system software update.

  1. Go to the  Apple menu or Dock, and choose “System Preferences”
  2. Select the “Software Update” preference pane
  3. Choose to update ‘macOS Big Sur 11.3.1’

macOS Big Sur 11.3.1

The update size for macOS Big Sur 11.3.1 is at least 2GB, despite containing two relatively small security fixes.

macOS Big Sur 11.3.1 Update Direct Download Links (IPSW)

Apple Silicon Macs can download macOS 11.3.1 as an IPSW file as well:

Using IPSW with Macs is much more complicated than with iOS/iPadOS, and therefore is not a suitable method of updating for the vast majority of users.

MacOS 11.3.1 Release Notes

Release notes accompanying the download are very brief, stating:

macOS Big Sur 11.3.1 provides important security updates and is recommended for all users.

For information on the security content of Apple software updates, please visit this website: https://support.apple.com/kb/HT201222

For more details, the security specific notes are as follows:

WebKit
Available for: macOS Big Sur
Impact: Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited.
Description: A memory corruption issue was addressed with improved state management.
CVE-2021-30665: yangkang (@dnpushme)&zerokeeper&bianliang of 360 ATA
WebKit

Available for: macOS Big Sur
Impact: Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited.
Description: An integer overflow was addressed with improved input validation.
CVE-2021-30663: an anonymous researcher

Separately, iOS 14.5.1, iPadOS 14.5.1, iOS 12.5.3, and watchOS 7.4.1 are also available to download with the same security patch.

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Posted by: Paul Horowitz in Mac OS, News

One Comment

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  1. Rob says:

    11.3 induced kernel panic (acc. to Apple Support) in my newish iMac…11.3.1 has sorted this so presumably contains bug fixes too

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