Disk Utility Bug in macOS High Sierra Exposes Passwords of Encrypted APFS Volumes in Plain Text [Updated] - MacRumors
Skip to Content

Disk Utility Bug in macOS High Sierra Exposes Passwords of Encrypted APFS Volumes in Plain Text [Updated]

by

Brazilian software developer Matheus Mariano appears to have discovered a significant Disk Utility bug that exposes the passwords of encrypted Apple File System volumes in plain text on macOS High Sierra.

disk utility password prompt

MacRumors confirmed our test password "dontdisplaythis" appeared as the hint

Mariano added a new encrypted APFS volume to a container, set a password and hint, and unmounted and remounted the container in order to force a password prompt for demonstration purposes. Then, he clicked the "Show Hint" button, which revealed the full password in plain text rather than the hint.

A second video with English system language is embedded below

MacRumors reproduced this behavior on a 2016 MacBook Pro running macOS High Sierra, including versions 10.13 and 10.13.1 beta. German software developer Felix Schwarz also shared a video of the issue on Twitter today.
The issue currently only affects Macs with SSD storage due to Apple File System compatibility, but APFS will eventually support machines with Fusion Drives as well. Schwarz believes users who haven't specified a password hint, or haven't used Disk Utility whatsoever, are probably not affected.

For clarity, this appears to be a bug within Disk Utility itself. When creating an encrypted APFS volume in Terminal with the diskutil command line utility, the actual hint is shown, rather than the password.

Mariano said he has reported the vulnerability to Apple. The company did not immediately respond to our request for a comment on the matter, but we'll update this article if we hear back.

Update: Apple has addressed this bug by releasing a macOS High Sierra 10.13 Supplemental Update, available from the Updates tab in the Mac App Store. Apple has also shared a support document outlining steps to back up, erase, and restore the encrypted APFS volume upon updating.

The bug has also been fixed in the base version of macOS High Sierra for those who have yet to install the full software update.

Tag: APFS
Related Forum: macOS High Sierra

Popular Stories

All Screen iPhone 2030 Feature Sans Text

iPhone 18 Pro: Nine Reasons Not to Upgrade This Year

Monday September 7, 2026 5:01 am PDT by
Apple is set to unveil new iPhone 18 Pro and iPhone 18 Pro Max models on Wednesday, September 9, and the devices are expected to feature a design that's largely similar to the iPhone 17 Pro models, with a peppering of enhancements inside. Major changes are not expected until next year, when Apple is expected to introduce a radically redesigned 20th-anniversary iPhone. If you're thinking of...
Read Full Article • 103 comments
iPhone 18 Pro Dark Cherry Feature

iPhone 18 Pro Reportedly Starts With 256GB of Storage

Thursday September 3, 2026 9:22 am PDT by
While the iPhone 17 Pro has double the base storage compared to the iPhone 16 Pro, there will apparently be no further increase this year. Taiwanese research firm TrendForce today again reported that the iPhone 18 Pro models will start with 256GB of storage, like the iPhone 17 Pro models. Minimum storage capacities by model:iPhone 16 Pro: 128GB iPhone 17 Pro: 256GB iPhone 18 Pro...
Read Full Article
apple watch series 12

Leak Hints at Four New Features for Apple Watch Series 12 and Ultra 4

Monday September 7, 2026 8:57 am PDT by
Ahead of the announcement of the Apple Watch Series 12 and Ultra 4 later this week, code in the watchOS 27 and iOS 27 betas points to a series of new features for the product line. The information comes from a new post from MacRumors forums member "pdfu." The findings include: New "Readiness" app: An all-new separate Watch app referred to in code as "Readiness," distinct from the...
Read Full Article • 101 comments

Top Rated Comments

masotime Avatar
masotime
117 months ago
Apple seriously needs to start hiring better QA engineers....
Score: 49 Votes (Like | Disagree)
I
IPPlanMan
117 months ago
But we need to have animated emoji faces...
Score: 26 Votes (Like | Disagree)
M
MasterMac
117 months ago
Does showing the password itself as the hint count as a password hint? ;)
Score: 23 Votes (Like | Disagree)
Frosties Avatar
Frosties
117 months ago
Thank you for the laugh. Great alpha software.
Score: 20 Votes (Like | Disagree)
S
smaffei
117 months ago
Apple seriously needs to start hiring better QA engineers....
Yes, there some HUGE problems with Apple QA these days.

iOS 11 is riddled with obvious bugs. I just got one about 10 minutes ago. Was just deleting a few voicemails (swipe delete) and the Phone App crashed. Then there is a very reproducible Messages bug where the keyboard obscures the last few messages and you can't get to them. Real rinky-dink stuff that should be caught.

I'm starting to think that Apple is relying too much on the Beta process to collect bugs instead of having robust internal QA.
Score: 18 Votes (Like | Disagree)
R
RMo
117 months ago
To be clear, the linked Twitter thread ('https://twitter.com/felix_schwarz/status/915851372217683970/video/1') suggests that this is a Disk Utility bug, where if you create a password-protected volume in Disk Utility it inadvertently sets the hint to the password itself. It's not a bug that allows the password itself to be uncovered via other means, which is what I originally thought this meant and which was surprising to me since the only way to do that should be computationally expensive brute-force methods (the data itself is encrypted with the password; it's not just artificially protected by one, and it shouldn't be possible to "reverse lookup" the password by any true means).
Score: 17 Votes (Like | Disagree)
Read All Comments