Security Update 2016-001 for OS X El Capitan and Yosemite Available

Sep 1, 2016 - 63 Comments

Security Update 2016-001 for El Capitan

Apple has released security updates for Mac users running OS X El Captain 10.11.6 and OS X Yosemite 10.10.5, recommending the updates for all users as they aim to improve the security of the Mac operating system.

The updates are labeled as Security Update 2016-001 10.11.6 for OS X El Capitan and Security Update 2016-005 10.11.5 for OS X Yosemite and are available now from the Mac App Store Updates section. The update size is quite small and should install quickly, but do remember to backup your Mac before installing any system software update.

The security updates also bundle a small update to Safari to bring it to version 9.1.3.

Release notes attached to the security updates are quite small but the related document on the Apple support website describes two primary issues that are patched in the release:

Available for: OS X Yosemite v10.10.5 and OS X El Capitan v10.11.6
Impact: An application may be able to disclose kernel memory
Description: A validation issue was addressed through improved input sanitization.
CVE-2016-4655: Citizen Lab and Lookout

Available for: OS X Yosemite v10.10.5 and OS X El Capitan v10.11.6
Impact: An application may be able to execute arbitrary code with kernel privileges
Description: A memory corruption issue was addressed through improved memory handling.
CVE-2016-4656: Citizen Lab and Lookout

Security updates are generally recommended for all Mac users to install as they aim to protect the computer from potential security risks or related harm.

Apple recently released a security update for iPhone and iPad users as well, versioned as iOS 9.3.5.

Troubleshooting Problems with Security Update 2016-001 for OS X El Capitan & Yosemite

Some Mac users have reported problems with their computer after installing the small security updates for OS X El Capitan or OS X Yosemite. The primary issues encountered seem to be one of the following:

  • Mac applications no longer work or launch at all, with an error message saying “You can’t open the application (app) because it may be damaged or incomplete”, and the app icons display as generic
  • Finder is extraordinarily slow to refresh folder contents
  • The Mac freezes or crashes on startup either at login or during a perpetual progress bar

You may be able to remedy the problems by booting the Mac into Safe Mode (reboot holding down the Shift key). Another possible solution to getting stuck on a white or black screen during system boot or login is to reset PRAM.

Persistent trouble after updating may require restoring the Mac from a Time Machine backup made prior to updating the system software.

What has your experience been with the latest Mac security updates? Did the installs go without a hitch? Did something go wrong and you found a solution to remedy an issue? Let us know in the comments.


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Posted by: Paul Horowitz in Mac OS, News


» Comments RSS Feed

  1. Bo Rutberg says:

    I got problems with the softwares on my MBP. It starts but the programmes does not work properly. Tried to use the cmd-R recovery to reinstall the system, but I was offered to install Sierra though my MPB runs on El Cap. And I don not want Sierra for several reasons. So I am stuck.

  2. KenJ says:

    Wasted 3 hours recovering system on my Macbook Air today

    A rotten Apple day, they should trash their QA team and start all over. Don’t update.

    Security update keeps stopping at 140mb after recovering machine …

  3. AndyJ says:

    Loaded on my i5 iMac (late 2013) El Capitan but corrupted Adobe Photoshop,irrecoverable permissions on Safari (won’t update now) and various other system areas won’t fix with disk repair. Numbers saves blank spreadsheets instead of the data in them and cannot load any new applications.

    Now re-building from scratch as it also screwed the Time Machine backup.

    Top Job Apple you get more like Microsoft with each software release.

  4. Roger100c says:

    My MacPro has just been bricked by this security update. Machine goes like a slug and starting any system application gives (eg) Contacts cannot be opened. May be damaged or incomplete. I ended up by doing a Time Machine restore which took 2 1/2 hours. I won’t be installing any more Security updates in a hurry!

  5. HaJee says:

    Since the update my iMac 27″ (end 2012) has sudden shut downs (complete powerloss). After a sudden shut down it takes minutes before I can turn my iMac back on (powerbutton does not respond). It happened to me 4 times in 2 weeks now. I brought it to a specialized Mac repear agent. They tried every possible hardware test and couldn’t find anything. Is anybody else experiencing this after the update? Could it be related? What can I do to rule this out?

  6. Sue says:

    Installed security-update-2016-001. My Mac has slowed right down. Anything to do with internet is pathetic. Emails send and receive very slow. Browsing very slow. Nothing wrong with my wifi. I am so upset. This is unacceptable. I don’t have use time machine regularly because I just back up my daily work. I didn’t realise that this could happen through trusted updates. :-(

  7. Ondaroad says:

    Just hangs after it says it is going to restart on this upgrade. Have reinstalled os, have reset Pram, have disconnected all usb’s still does the same thing. :( ?? Help?

  8. Kerry says:

    After the latest security “update” Time Machine acted like it was making a virgin BU which distinctly takes a lot of time. I stopped it by clicking the x in the time Machine Preferences panel. Clicked the external HD icon and all was empty. So…….did someone steal the files, are they in cyberspace for when I continue the backup(I cancelled it), or if I request a backup, will I have to wait for a virgin back up by Time Machine which will take 1 1/2 to 2 days? Until resolved, I’ll just drag drop the main files onto the hard drive. Simple and no fuss. Thanks a lot Apple!

    • Kerry says:

      Went to copy main folder to drag a copy to another HD and got the message “You can’t copy the item “” because its name is too long or includes characters that are invalid on the destination volume.” Never had any problem with folder or document titles before…..What’s going on…..

  9. Dan says:

    This is my second mess up from a “security Update” within a short time. The first time only a complete delete and reinstall from an external boot drive with the El Capitan installer and then restore from an older Time Machine backup and a waste of 8hours of my precious lifetime did the trick. This time, my 2009 MacPro started up to the login screen but loggin in with my main account just showed the turning wheel forever. Interestingly a second accout could log in with no issues. Although I performed the procedure found here
    it did not help. So I am restoring from my recent timeMachine backup. Unfortunately, I found this post only after starting the restore. That could have solved my issue as it seems to be isolated to one user only.

  10. Kim says:

    I too am crippled. Updates applied last night. Mac was completely frozen this morning and everything was slow to respond. Finally got into poweroff. Now Mac won’t come on. Powers back off when the status baris 3/4 way completed.

  11. Sandeep Sabharwal says:

    Was prompted this morning to carry out the latest security update on my MacBook Pro (1.5 yrs old). System never came up, it looks dead. Tried pressing combinations of all buttons, including the recommended Command+Option+P+R+Power. What should I do now ?

  12. Denise says:

    This update seems to have crippled my Mac completely….I can’t even restore from time machine been trying for 10 days bad tried everything I can think of; even in safe boot it’s crippled and I can’t seem to run it in diagnostic mode either :-(

  13. Mark phillips says:

    My partners mbp updated fine. BUT mine is now being restored for the 4th time in a week from timemachine for the problems mentioned above. Appalling silence from APPL as we waste $m’s collectively. Too much time wasted for me. APPL support is in a downward spiral. Time for a new competitor to emerge and get back to a solid experience.

  14. blasev says:

    imac 2011, works fine. at first startup after update reboot, I notice long delay while the screen is black. but after I waited for about 5 minutes, everything goes runs well, no problem with wifi connection and all data intact

  15. Jeanne says:

    I had the same problem as Ash. Download gets part way done and stops. I’ve tried and re-booted several times, and after reading these, I’m stopping!

  16. Dana Charbonneau says:

    Works okay but I’m now seeing .DS_store files all over the place

  17. No way says:

    Mini and 3 mbp took under 10 min each no problems at all.

    Data rule #1 back up first. Anyone losing data has no one to blame but themselves.

  18. Tobias says:

    Deleting all folders in /private/var/folders worked
    Booted the Mac in recovery, used Terminal rm -rf
    Lost a few finder settings, no data loss, system works again.

    • Bobbie says:

      I have seen this solution a couple times now,
      Can you walk me through this process? Do you have to reboot to an external drive to access and delete these files? I have tried safe mode restart but my iMac 2010 is still dragging and hanging up to an unusable point. My most recent backup was May so I would prefer not to use it but will if I have to. Thanks

      • grant says:

        Jedi describes removing the /private/var/folders/ directory contents here:

        Basically condensed it would require this:

        1) Startup this Mac with any external OS drive (boot disk, recovery disk, etc)

        2) On the problem disk (Macintosh HD or whatever the name is) use Go to Folder (command shift G) and enter /private/var/folders/ and trash ALL contents in that folder

        3) Empty the trash and reboot to main Mac OS.

        Theoretically you could probably do it from Internet Recovery or Recovery HD with Terminal as well with:

        cd /private/var/folders/

        Then use wildcards to delete the folders contents, which is risky because wildcards will delete EVERYTHING if they are not closely controlled with exact syntax:

        rm -rf /private/var/folders/??/

        Or with star/asterisk which is the riskiest, because * means EVERYTHING it touches which is why it must be specified exactly to the subfolders beyond /private/var/folders/

        rm -rf /private/var/folders/*

        I can’t say it enough, this is highly risky and may not even work. Is that worth the risk? I don’t know, but I would not recommend it unless it is last resort AND you have an ultimate backup just in case to resort to. It may be better to just reinstall Mac OS and then skip the security update until Apple can fix it or go to MacOS Sierra.

        • lborgesmoraes says:

          Hi. I confirm that deleting everything in /private/var/folders/ fixed the problem. Only issue was I had to boot using an external drive as El Capitan in the internal HDD was incredibly non-responsive. By booting from an external drive I could trash the content then turn-off and boot from internal drive. My MBPro Mid 2010.

  19. Christine says:

    Hi, I actually can’t do the security update on my mac mini as when I try to update, a prompt opens and says I have to click ‘Show Details” but when I do nothing happens. Anyone here have the same problem?

  20. Ash says:

    Unable to update. It gets stuck at 149 MB all the time. Looking at comments, I am in no hurry now.

    • Peter says:

      After this update my 27″ i7 2009 iMac is cooked, no option to get to my external bootable drive anymore! Apple just screwed me big time.

    • Mike says:

      Yes, I am getting the same behaviour – the download simply stops after 149Mb.
      From what I read here, I am glad it was failing.
      I won’t upgrade until this issue is properly resolved.

      fyi… I am using a 2007 MAC MBP

  21. Tobias says:

    Bricked my iMac. This is not the first time an Update kills my Macs. Apple is doing a bad job, since this ruins my whole day.

    Making another backup via Network, just in case the TimeMachine backup wont work.
    I will then have to restore the Mac, cant start any App.
    Sadly SSH is off
    Fusion Drive prevents hooking up the iMac drive to another Mac

  22. Ruurd says:

    Four different types of MacBook Pro here, fat 13, fat 15, slim 13 and slim 15 – no problems at all.

  23. Carl says:

    My iMac became unable to network wirelessly and even failed direct Ethernet connection (with two different cables). I restored from a Carbon Copy Cloner by starting up from the clone drive and cloning back to Macintosh HD. All is well again, but the App Store is notifying me that I need to perform that (accursed) security update. I sure hope the next update from Apple is more carefully constructed.

  24. Guy says:

    Security update was also released for OS X Mavericks

  25. Jedi says:

    Possible fix to having a Mac that is messed up after installing Security Update 2016-001 on El Capitan:


    I’ve had this problem right after some updates too. And it was not possible to run the Terminal and Console.

    The only solution that helped:

    1) Startup this Mac with any external MacOS (Yosemite, El Capitan on external disk).

    2) On the problem disk (Macintosh HD in my case) Go to Folder /private/var/folders/ and trash ALL contents (enter admin password).

    3) Empty the trash and reboot to main MacOS.

    P.S. Safe boot did not help. Partially cleanup /private/var/folders/ did not help too.


    This was found on Discussions Apple and I can not confirm if it works yet but it has three helpful points on the Discussions baord so it might be helpful.

    You might need to “enable hidden files view” first to find the proper folders inside /private/var/folders/.

    The big thing as always is make sure you backed up your Mac first before installing the update so that if it breaks you can fix it, or if you try that trick and it makes it worse you can fix it.

    Good luck people, what a nuisance!

  26. Constable Odo says:

    Dammit. It says I can’t install the Combo updater on my drive because it doesn’t meet the requirements. WTF?

  27. Constable Odo says:

    That September Security update definitely did something nasty with my i7 Mac Mini. The Finder has become very unresponsive with an intermittent spinning pinwheel. It was running perfectly before the update. I’ve just run Onyx with full automation and that didn’t help. It’s been rebooted a couple of times. I’m going to try to run the 10.11.6 combo updater and see if that helps. I didn’t have a backup because I only use the Mac Mini for small tasks and running Kodi on my HDTV. I thought that security update was harmless enough, so I decided to run it and I should have left well enough alone. Honestly, I’ve never had any problems like this before with updates in the last five years on any of my Macs.

  28. Wharf Xanadu says:

    I want the update but I will wait a little while to make sure there is no problem. Maybe wait for Sierra if it’s due in October 1.

  29. dan says:

    I am having problems with install also. I had go back to backup I made the day before. I let Apple fix it before I try to install again.

  30. Rick says:

    Bricked my iMAC 2010. Two endless calls with Apple support resulting in no solution. Apple has a serious QA issue…

    Thank goodness for Acronis True Image!

    Recommend not updating

  31. Keith says:

    I’m seeing a lot of reports on Twitter and macForums that suggest problems with the update. One guy reports his entire campus Mac network is messed up from the update.

    I wonder if all the problematic Macs have NVidia graphics cards, there are mentions of problems with nvidia drivers with the update?

  32. Downloaded, installed, rebooted. Seemed to have been installed. Except App Store Software Update seemed to think it still needs to be installed, or that my computer needs to be rebooted again. Well, the computer has been rebooted twice and still Software Update says “Reboot Required.”

  33. Maduro says:

    Anything went fine, it took less than 10 minutes to download and install (iMac , Late 2013, 10.11.6 (15G1004), 8 Gb ram, 1 Tb SATA HD)

    • Jim Murphy says:

      Went OK on my laptop.

      But this seemed odd on my iMac:

      After it restarted, and I had to click continue a couple of times, my info came back, and then the screen partially darkened and it said “Loading Applications.” I have never seen that before. Is this common?

  34. Evgen says:

    Installed on Macbook Pro, late 2008. 8 Gb RAM, 500 Gb SSD, no issues. Took approx 5 min

  35. loyal says:

    Installed in less than 5′ (just 4′ to download from the AppsStore): no issues at all.
    [MBP 13 early 2011, 8 GB RAM, 500 GB SSD]

  36. Cerebro says:

    The reports of “bricking” had me a little worried, at first. The install went just fine on my MacBook Pro. It did seem to take a bit longer to install than I was anticipating. Other than that, no issues.

  37. john doe says:

    Works fine for me.. tried on two different mac book air.

  38. imacconvert says:

    Glad I read these, good people report what they encounter to help others.
    I shall wait and see too.

  39. Motley says:

    Basically the same issue. Tried the update twice, restoring from Time Machine in between. No applications would launch after the patch, basically gave an error about “the application can’t be opened”.

  40. Bob says:


    I just wanted to let you know that my Mac Pro is bricked by security update and I’m so disappointed. So, beware and do not update it until Apple resolves this issue. Apple is recently doing a lousy job since its legendary founder Steve Jobs passed away. Sad!

    • Erick says:

      Same thing happened to me. The last Yosemete security update bricked my Mac Pro. Thank God I had another one. I cloned the drive and was able to get my files out of it. But still lost alot of stuff. Suggest don’t update until more info is out there regarding that last update..

  41. Jeff Racz says:

    Bricked my MacBook Air. Basically removed all programs in the Applications folder.

    • Lymis says:

      Did that to me, too. All apps removed except a couple. One of the ones that was missing was Disk Utility. Safari worked, but only shakily.

      I had to restore from a time machine backup. Once I did, I got the black screen with a moveable cursor about halfway through the startup process.

      Turned out that something about the install/restore reset my login preferences to require me to type in my username and password. But with the screen black, I couldn’t. I started up in safe mode and then reset the preferences so as not to require the password and it completed the login normally.

      I’m holding off on reinstalling the security update.

  42. shpankey says:

    Weird, I did this update and it seemed like a major update. It did two reboots and took about 30 minutes.

  43. Medhat says:

    This update bricked my iMac, notified apple, restoring from timemachine

    • Uber Stein says:

      Well that’s not good, such a small security update should have basically no impact.

      Unfortunate if the case, this is why many users just don’t update their Apple software anymore. Too unreliable and too hard to predict. I can’t afford to take 5 hours in the middle of my day to restore my Mac from Time Machine and neither can most people.

      I guess I will hold off too then for now.

    • Medhat says:

      Tried nearly the suggestion (except delete /private/var/folders) to no avail. My iMac is late 2015 i7, 5K retina so it was a total surprise that the patch would;t install. It installed fined on 2 other older macs! Will wait for OS 10.12 and see what happens

  44. Mark says:

    You forgot to mention todays Safari update to version 9.1.3 for Mavericks

    • Moonsteen says:

      Bricked my Mac Mini. No Apps left visible and no direct acces to document folders.
      Managed to restore to previous state by restart on external drive (instact os there) and reinstall Newest El capitan from Appstore on top of the corupted system. Be sure to back up before this update

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