OS 26.6 Delivers Massive Number of Security Fixes

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Originally published at: OS 26.6 Delivers Massive Number of Security Fixes - TidBITS

Apple has released what could be the final bug fix releases of the OS 26 operating systems, primarily to deliver fixes for a massive number of security vulnerabilities, none of which are being exploited in the wild. macOS 26.6 Tahoe, iOS 26.6, and iPadOS 26.6 also optimize the Spotlight index to prepare for their upcoming version 27 releases. For watchOS 26.6 and visionOS 26.6, the release notes merely promise bug fixes and security updates; Apple hasn’t issued the tvOS 26.6 release notes yet.

During WWDC, Apple acknowledged that Spotlight doesn’t always find what you know is there, so the company has rearchitected the search index to be more stable, comprehensive, and responsive; see “WWDC26 Keynote Shows Apple’s Tacit Acknowledgment of External Pressures” (8 June 2026). This change suggests Apple believes optimizing the Spotlight index for the new architecture now will provide a benefit during the upgrade.

As usual, Apple didn’t expand on what bugs might have been fixed in any of the primary release notes, but in the developer release notes for macOS 26.6, the company documents fixes for three bugs:

  • Garbled screenshots in Messages: HDR screenshots could appear garbled when sent in Messages.
  • Incorrect Intel-based app identification: When you launch an Intel-based app in Tahoe, it displays a notification that support will be ending. Those notifications incorrectly identified some apps when a system plugin loader, such as a Color Picker or Print Dialog Extension, loads x86 code into the host process.
  • HealthKit stats abnormally high: Certain HealthKit queries—particularly for metrics like Resting Heart Rate—could return erroneously high values.

The macOS 26.6 developer release notes also said that Apple has deprecated Encrypted HFS+ as a drive format, and it will not be supported in macOS 28. That’s over a year from now, but if you’re still using Encrypted HFS+ volumes for backup, you’ll want to transition those to APFS-formatted drives. Howard Oakley has written more about what the deprecation of Encrypted HFS+ entails.

When it comes to security fixes, there are more than I have ever seen in a single release set, likely due to the assistance of AI tools in finding vulnerabilities:

I wouldn’t be surprised if we see iOS and iPadOS 18.7.10 updates to bring some of the security fixes to the small number of devices running iOS 18 that cannot upgrade to iOS and iPadOS 26: the iPhone XS, iPhone XS Max, iPhone XR, and iPad (7th generation).

Happily, Apple doesn’t identify any of these security vulnerabilities as being exploited in the wild, so although it’s important to install these updates, you should be able to wait a few days to make sure no unanticipated problems appear. Like issues with VNC?

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VNC Failure after macOS 26.6 Update
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I confirm that Safari 26.6 is available for Sequoia and Sonoma.

The usual security notes are now online, and I’ve updated my M1 MacBook Air to Sequoia 15.7.8 + Safari 26.6. So far, so good.

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and iOS 26.6 prevented cellular voice from functioning, at least for T-Mobile. BUT FIXED!

SOS will be displayed on the top right of the screen in place of the traditional cellular signal bars.

I’ve rebooted my iPhone 15 Pro (which was required a couple times over the last years when cellular voice stopped working) and I’ve turned off “Use this line” in Settings, and back on. Still “SOS”.

As soon as I posted that, I picked up the phone and it displayed the cellular signal bars again. The lesson is:

You may need to wait 15 minutes or so after updating to iOS 26.6 for cellular voice to start working again.

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I believe It was just a coincidence - there was a T-Mobile outage starting at about 4 pm eastern time, for all devices, not just iPhones with 26.6.

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Certainly an outage was another possibility I considered…later.

This happens so often at work as well: whatever we just changed is immediately suspected as the most likely cause of a problem.

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Thanks! They were just slow in getting that link up—I’ve tweaked the article.

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I updated 2 Macs to macOS 26.6 today, and now neither of them can be remotely controlled via VNC apps on my iPad/iPhone. Native screen sharing between the upgraded Macs works fine, and I can still control the upgraded Macs fine from a non-upgraded Mac still running 26.5.whatever.

I normally use RealVNC Viewer from the phone or iPad to connect with username and password, and now it gives an error saying either that the VNC server is not running or it’s running an incompatible version. When I set the Mac to allow VNC viewers to connect with simple password, same problem.

Tried multiple reboots of both the Macs and iOS devices. Did not go spelunking in the logs for errors. Did verify that the upgraded Macs are still listening on port 5900, so that didn’t change at least.

Anyone got any similar experience and/or advice? Thanks in advance!

-JYK

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Well, since I wait a year before downgrading, I may start installing iOS 26 on my iPhone 12, 3 iPads, and 2 Apple TVs this weekend, starting with the oldest and least used. At least I don’t have to do my iMac and MBP since they are maxed out at High Sierra and Monterrey respectively.

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Wow… 11GB on the iPhone 17Pro download. I missed the MacOS size but did that first, then backed up the phone and now letting it update.

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It is almost certainly the T-Mobile outage. I had updated my iPhone before walking to lunch and successfully used its cellular connection to read several articles and even create a mobile driver’s license for my Apple Watch. At one point on my way home, I had no issues, but a few blocks from home I lost cellular connection and remained without it for several hours.

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Spotlight doesn’t always find what you know is there, so the company has rearchitected the search index to be more stable, comprehensive, and responsive;

I for one can attest to a related problem experienced by several people, namely Mail’s search envelope can become irremediably corrupted – and trying to restore it fails. The result is false positives and false negatives in Mail search. I hope their update fixes this. Will see. I’ve had to resort to using a collection of Mail apps and webapps but without complete coverage.

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Mail.app’s focus bug is now fixed in macOS 26.6.

Starting from macOS 26.5, I noticed the following bug. (It persisted in 26.5.1 and 26.5.2.)

  • Open Mail.app.
  • Select an email message (in the topmost message list.)
  • Press Delete (the message moves to the Trash mailbox.)
  • Press command-shift-Delete. Then a dialog appears, asking if I really want to completely remove the message(s) in the Trash mailbox.

Then, I press the Return key. In macOS 26.4.1 and earlier, it successfully pressed the ‘Delete’ button on the dialog, the Trash mailbox became empty, and the dialog went away.

But not in macOS 26.5. The Return key just causes the beep sound, the button is not pressed. I need to USE THE MOUSE to click anywhere (other than the buttons) on the dialog, and then Return key successfully presses the ‘Delete’ button. And thereafter, the problem goes away. Return key never causes a beep any more, as long as the Mail app keeps running. Then, once I quit Mail.app and relaunch it, then the problem reappears. The ‘Really want to delete?’ dialog doesn’t see the Return key press and beeps, until I USE THE MOUSE to click on the dialog. (I reported this to Apple Support.)

Now, today, I installed macOS 26.6, and I see this bug is gone. Pressing Return key never causes a beep on the dialog; Deleting an email message doesn’t require the mouse any more.

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And more from Howard Oakley on Encrypted HFS+ today.

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I noticed today that a few apps required significantly longer than usual to open after I installed yesterday’s update to Sequoia 15.7.8.

For example, Music.app took well over a minute to open. Outlook and a few others also took noticeably longer than usual. Once opened, everything seems fine. Interestingly, other apps, including rather large ones with a lot of loadable components, opened without delay.

Is anyone else seeing that?

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When I launched Health on my phone (to log my weight) this morning, it took a long time to come up. The app launched quickly, but it took about 30 seconds for my three pinned stats to appear on the main page.

I assume that Apple turned on some new authentication system, but they’re using a lazy-activation mechanism (only do the work when the app is launched) in order to avoid the big CPU/network hit that would be caused if everything was re-authenticated up front.

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Noticed the benefits of this already just hours after installing 26.6. Now my Spotlight immediately pushes to the top a doc that keeps getting launched through Spotlight even when just entering the first few letters of the doc’s filename. Just like it used to work. Great update if you, like me, use Spotlight as a KB-based doc/app launcher. :slight_smile: :+1:

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Mac OS 26.6 killed my monitor preferences, and I can’t seem to get them back. When it rebooted into 26.6 my resolution was jacked up, and brightness and HDR settings disappeared. Also can’t access the refresh rates monitor can support.

Mac Studio M4 Max, with Asus ROG XG32UCG 31.5" 4K HDR 160Hz monitor, no issues until now with settings.

I tried rm -f ~/Library/Preferences/ByHost/com.apple.windowserver*.plist to no effect…

Not a happy camper, if anyone has any ideas I’d appreciate it!

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Darn!

I forgot to run @ace’s SetShot before I updated!

If anyone hasn’t updated yet, please consider giving SetShot a try.

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Ran it right before and after the 26.6 update. No changes to any of my Settings this time.

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This feels like the “iOS update re-index like crazy for a week so you feel like you need to buy new devices” cause it kills your battery for a while. Am I the only one that feels like that?