Should you update to macOS Sequoia 15.7.8?
No: install macOS Sequoia 15.8.2 instead. macOS Sequoia 15.7.8 is a security update Apple released on 27 Jul 2026 for Mac. It fixes 148 security flaws.[1] None of them is known to be used in attacks.
It has since been replaced by macOS Sequoia 15.7.9, released 6 Aug 2026, which includes all of its fixes. If you’re on an older version, install that instead.
Should you update?
No: install macOS Sequoia 15.8.2 instead. macOS Sequoia 15.8.2 came out on 26 Oct 2026 and includes every fix in macOS Sequoia 15.7.8, so there’s no reason to stop at this one. Software Update offers the newest version your Mac can run.
Is macOS Sequoia 15.7.8 still safe?
Not any more. The 4 updates since, up to macOS Sequoia 15.8.2, fix 377 security flaws that macOS Sequoia 15.7.8 doesn’t, and each became public the day its fix shipped. Installing it is safe: get it only from System Settings → General → Software Update, never from a link in an email, text or pop-up.
What it fixes
Apple lists 148 security flaws across 72 parts of macOS. For each, Apple says what an attacker could have done before the fix.[1]
| Part | Flaws | What an attacker could do |
|---|---|---|
| Kernel | 22 | An app may be able to cause unexpected system termination or corrupt kernel memory |
| Model I/O | 9 | Processing a maliciously crafted image may corrupt process memory |
| HFS | 7 | A remote user may be able to cause unexpected system termination or corrupt kernel memory |
| ImageIO | 7 | Processing a maliciously crafted image may corrupt process memory |
| Disk Images | 5 | An app may be able to elevate privileges |
| curl | 4 | Authentication credentials may be sent to a server on another origin |
| SceneKit | 4 | Processing a maliciously crafted file may lead to unexpected app termination or arbitrary code execution |
| CoreAudio | 3 | Processing a maliciously crafted audio file may corrupt process memory |
| CUPS | 3 | A malicious app may be able to gain root privileges |
| Screen Sharing Server | 3 | An app may be able to intercept network connections intended for another process |
| SMB | 3 | Connecting to a malicious SMB server may lead to unexpected system termination |
| Accounts | 2 | An app may be able to gain root privileges |
| afpfs | 2 | A remote attacker may be able to cause unexpected system termination or corrupt kernel memory |
| Apple Account | 2 | An app may be able to access sensitive user data |
| AppleRAID | 2 | A local user may be able to read kernel memory |
| 57 other parts | 70 |
How to update, and how long it takes
It takes 15 to 45 minutes in all: a few minutes to download, then it prepares, installs and restarts, and you can’t use the Mac while it installs.
- Back up first if you can.iCloud backup or your computer. Updates rarely go wrong, but a backup makes it painless if one does.
- Open Apple menu → System Settings → General → Software Update.Your Mac shows the newest version it can run. Tap or click Update Now, or Upgrade Now for a new major version.
- Leave it plugged in.It downloads, prepares and restarts. Expect 15 to 45 minutes.
- Turn on automatic updates.In the same place, under Automatic Updates, turn on both downloading and installing security responses and updates.
To check it worked: Apple menu → About This Mac shows the macOS name and version. It should say Sequoia 15.7.9 or later.
Older devices
The same day, Apple released macOS Tahoe 26.6 (170 security flaws) and macOS Sonoma 14.8.8 (137 security flaws) for Macs that stay on an older version. Each fixes the same holes where they apply.
Before and after
- After: macOS Sequoia 15.7.9, 6 Aug 2026, 1 security flaw
- macOS updates, every release and the latest version
- Updates, the latest version of everything HARD tracks
References
- ^ Apple. “About the security content of macOS Sequoia 15.7.8”, 27 Jul 2026.