macOS Sequoia 15.7.4 Patches 36 Security Flaws Your Older Mac Still Has

Apple released macOS Sequoia 15.7.4 on February 11, 2026, patching 36 security vulnerabilities across 24 core system components including Wi-Fi, Kernel, Sandbox, and Siri. The update targets every Mac running macOS Sequoia, which means Intel MacBook Pros from 2018, Intel iMac Pros from 2017, and every Apple Silicon Mac that hasn't moved to macOS Tahoe yet. The tricky part is that Sequoia won't receive security patches forever, and several of the flaws fixed in Tahoe 26.3 on the same day were not patched in Sequoia at all.

That gap creates a real decision point. You can install 15.7.4 right now and stay protected for the near term, or you can start planning the move to Tahoe (or new hardware) before Sequoia falls off Apple's support radar entirely. Both paths require a specific set of steps, and the wrong order can cost you data or accidentally push you onto an OS your Mac wasn't ready for.

What macOS Sequoia 15.7.4 Actually Fixes

The 36 CVEs span components that handle everything from how your Mac connects to Wi-Fi networks to how apps interact with the system Sandbox. Apple's full security notes list each vulnerability, but the ones that matter most for day-to-day use fall into a few categories.

Wi-Fi memory corruption (CVE-2026-20621) allowed a nearby attacker to corrupt kernel memory through crafted Wi-Fi frames. If you use your Mac at coffee shops, coworking spaces, or airports, this one alone justifies the update. The fix required changes deep in the Wi-Fi driver stack, and there is no workaround short of disabling Wi-Fi entirely.

Sandbox escape (CVE-2026-20628) let a malicious app break out of its restricted sandbox environment and access files it should never touch. Apple tightened the logic checks in the sandbox enforcement layer. A second sandbox-adjacent flaw in libxpc (CVE-2026-20667) gave apps another route out through XPC service calls.

Kernel privilege escalation (CVE-2026-20626 and CVE-2026-20671) gave attackers two separate paths to gain elevated system privileges. The first exploited a logic error; the second targeted network interception. Both are patched through improved validation in the kernel itself.

Siri lock screen information disclosure (CVE-2026-20662) meant someone with physical access to your locked Mac could extract information through Siri that should have remained behind the lock screen. Apple strengthened the authorization checks that Siri performs before responding on locked devices.

Seven additional Multi-Touch vulnerabilities (CVE-2025-43533 through CVE-2025-46305) could crash your system through a malicious HID device, meaning a compromised USB accessory plugged into your Mac could trigger a kernel panic. WindowServer, CoreAudio, CoreMedia, and ImageIO round out the list with memory handling fixes that prevent crashes and potential code execution from malformed media files.

Which Macs Need This Update

macOS Sequoia runs on Intel Macs from 2018 onward and all Apple Silicon Macs. But the Macs that need 15.7.4 most urgently are the ones that cannot upgrade to macOS Tahoe. These machines will lose Apple's security support entirely once Sequoia reaches end of life, expected sometime in late 2027 based on Apple's historical pattern of supporting the current OS plus two prior versions.

The Intel Macs stuck on Sequoia as their final supported macOS version include the 2018 MacBook Pro (13-inch and 15-inch), the 2018 MacBook Air, the 2018 Mac Mini, the 2019 iMac (21.5-inch and 27-inch Retina), and the iMac Pro from 2017. These machines all received macOS Sequoia but were dropped from macOS Tahoe's compatibility list when Apple tightened hardware requirements for Tahoe's Liquid Glass rendering pipeline.

A handful of Intel Macs did make the Tahoe cut: the 2019 Mac Pro, the 2019 MacBook Pro 16-inch, the 2020 iMac, and the 2020 MacBook Pro 13-inch (the four-Thunderbolt-port model). If you own one of these, you have the option to move to Tahoe directly. Everyone else on Intel is looking at Sequoia as the last stop.

How to Install 15.7.4 Without Accidentally Upgrading to Tahoe

Apple's Software Update panel in System Settings shows both macOS Tahoe and the Sequoia security update on the same screen. The Tahoe upgrade is more visually prominent, and it is disturbingly easy to click the wrong button. MacRumors forum users have reported accidentally upgrading to Tahoe when they intended to install a Sequoia security patch, and rolling that back requires a full erase and reinstall.

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Before touching Software Update, run a full Time Machine backup. Connect an external drive, open System Settings, select General, then Time Machine, and verify that your backup completes with a current timestamp. If your backup drive is aging or you don't have one, this is the moment to invest in reliable external storage. The Samsung T7 Shield handles Time Machine backups at 1,050 MB/s over USB 3.2 Gen 2, and its IP65 dust and water resistance rating means it survives desk spills and bag drops that would end a bare-bones enclosure. The rubberized shell has a satisfying grip to it, the kind of slight texture that keeps the drive planted on a desk surface without sliding around, and the USB-C cable seats firmly with none of the wobble you sometimes get from cheaper drives.

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Once your backup is verified, open System Settings, click General, then Software Update. Look below the macOS Tahoe section for a smaller line that reads "macOS Sequoia 15.7.4" with a "More Info" link. Click that link specifically. Read the description to confirm it says "This update provides important security fixes" and shows build 24G517. Click "Update Now" on that specific panel. Do not click the larger "Upgrade to macOS Tahoe" button above it.

The installation requires a restart. Plan for about 20 minutes of downtime on an SSD-equipped Mac, potentially longer on older machines with spinning hard drives.

The Security Gap Between Sequoia and Tahoe

Howard Oakley at The Eclectic Light Company noted something important when 15.7.4 shipped: many vulnerabilities patched in macOS Tahoe 26.3 were not patched in Sequoia. Apple's security page for Tahoe 26.3 lists 52 CVEs. Sequoia 15.7.4 lists 36. The gap means at least 16 known vulnerabilities exist in Sequoia that Apple chose not to backport, either because the fixes require Tahoe-specific frameworks or because Apple is prioritizing forward development.

This is consistent with Apple's historical approach. The company maintains security patches for the current macOS plus two prior versions, but the older versions always receive fewer fixes. If you want the full set of patches that Apple is willing to ship, macOS Tahoe is the only option. For a deeper look at the security layers that macOS handles versus the ones you need to manage yourself, Zone of Mac covered the gaps that macOS Tahoe cannot close on its own.

The table below compares your three options after installing macOS Sequoia 15.7.4, so you can decide the right path for your Mac.

When Staying on Sequoia Stops Making Sense

The honest answer depends on your threat model and your patience for diminishing returns. If your 2018 MacBook Pro still runs every app you need and you work primarily from home on a trusted network, Sequoia 15.7.4 keeps you covered for now. Apple will likely ship 15.7.5 and possibly 15.7.6 over the coming months, buying you time into early 2027.

But if you handle sensitive client data, connect to public Wi-Fi regularly, or rely on apps that are starting to require macOS Tahoe as a minimum, the clock is already running. The Mac Mini M4 starts at $599 and packs Apple Silicon M4 with a 10-core CPU, 16GB of unified memory, and hardware-accelerated machine learning that powers Apple Intelligence. The form factor is smaller than a paperback novel, and the power button on the bottom of the unit has a satisfying tactile click that belies how much computing power sits inside. The fan stays inaudible during normal desktop workloads, and even under sustained compilation or video export, it barely whispers. I mention this because the 2018 Mac Mini's fan was notorious for ramping up during routine Spotlight indexing.

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Migration Assistant handles the transition from Intel to Apple Silicon seamlessly. Connect both Macs to the same Wi-Fi network (or use a Thunderbolt cable for speed), launch Migration Assistant on the new Mac Mini, and follow the prompts. Your apps, files, settings, and even your desktop wallpaper transfer over. Some older 32-bit apps won't survive the move, but those stopped working in macOS Catalina back in 2019 anyway. For a companion guide to verifying your new Mac's security posture after migration, Zone of Mac has a walkthrough of scanning your Mac for malware using built-in macOS tools.

Accessibility and Clarity

macOS Sequoia 15.7.4 does not introduce new accessibility features, but several of the security fixes directly improve the experience for users who rely on assistive technology. The Voice Control crash fix (CVE-2026-20605) resolves a system process failure that could interrupt dictation and voice navigation mid-sentence. For users who depend on Voice Control as their primary input method, this was a functional blocker, not just a security concern.

The Siri lock screen fix (CVE-2026-20662) strengthens authorization checks without changing Siri's behavior for users who rely on voice commands to interact with their Mac while performing other tasks. VoiceOver users navigating the Software Update panel should note that the Sequoia 15.7.4 update appears below the Tahoe upgrade section. Use the arrow keys to move past the Tahoe description to find the Sequoia-specific update. The "More Info" link for Sequoia 15.7.4 is a standard button element that VoiceOver announces correctly.

For cognitive accessibility, the installation process itself follows a predictable three-step pattern (backup, click, restart) with no branching decisions or nested menus. The primary risk, accidentally clicking the Tahoe upgrade instead of the Sequoia patch, is a layout concern rather than a complexity concern. Apple could improve this by separating security patches from major OS upgrades into distinct sections within System Settings. Apple's Security framework documentation provides additional technical context on how these patches integrate with the broader macOS security architecture.

Quick-Action Checklist

1. Connect an external drive and verify a fresh Time Machine backup completes successfully.
2. Open System Settings, click General, then Software Update.
3. Scroll past the macOS Tahoe section to find "macOS Sequoia 15.7.4" and click "More Info" on that specific entry.
4. Confirm the build number reads 24G517 and click "Update Now" on the Sequoia panel only.
5. Allow 20 to 40 minutes for installation and restart.
6. After restart, open System Settings, General, Software Update again to confirm "macOS Sequoia 15.7.4" shows as current.
7. If you own a Tahoe-compatible Mac and are ready to migrate, download macOS Tahoe from the same Software Update panel after verifying your backup.
8. If your Mac cannot run Tahoe, budget for a hardware upgrade before Sequoia's estimated end-of-life in late 2027.