Reactivate Microsoft Office Equation Editor 3.0

[German]On January 9, 2018, Microsoft released security updates for Microsoft Office. Subsequently, users discovered that the formula editor was missing in Word or other Office modules. Here is some information and a solution how to get the Equation editor back.


Some background information

Equation Edition s a sad chapter in Microsoft Office. In the summer of 2017, researchers from the cyber security company Embedi discovered a CVE-2017-11882 vulnerability in the Office formula editor. An article about the bugs can also be found here. i. It turned out that this vulnerability was present in all Microsoft Office and Windows versions for the last 17 years.

The equation editor EQNEDT32.EXE, which was included in Microsoft Office until 2007 but was still shipped with Office, received an update to close the gap on November 2017 patchday (I mentioned it in the blog post Microsoft Office security updates (November 14, 2017)).


While Microsoft replaced the old EQNEDT32.EXE component with a new component in 2007, the older file is still included in all Office installations so that users can load and edit equations that were created with the old component. Microsoft had to take action because hackers already exploited this vulnerability (see Hacker are misusing CVE-2017-11882 in Office EQNEDT32.EXE).

In my German blog post Hat Microsoft Zugriff auf Teile des Office-Quellcodes verloren? I had also pointed out that Microsoft has patched the formula editor binary, which is a bit obscure. The speculation was that Microsoft no longer has access to the source code.


And there is another strange thing. In Office 2003, the equation editor is not vulnerable. The company Office 0patch had informed me by mail about the following:

We read your article on our analysis of the Equation Editor patch and would like to clarify that Office 2003 is, peculiarly, not vulnerable because for some reason, its Equation Editor executable is different and seems to have been built (or manually patched) 5 years later than the same executable in Office 2007, 2010, 2013 and 2016/365.

So Microsoft has patched the formula editor in Office 2003, while in later versions the vulnerable editor was delivered.

Update removes equation editor 3.0

In January 2018, Microsoft rolled out numerous security updates for Microsoft Office. I had described these in the blog post Microsoft Patchday: Office, Flash, Windows (January 9, 2018). In this German comment blog reader Joschi points out that the updates will remove the equation editor.

Office 2010 eqnedt322010-kb4011610 deletes the installed equation editor.

Therefore it is essential to uninstall and hide the update!

Also within this German Microsoft-Answers forum post someone noticed. There are other places to find it. On the PC, when clicking on a formula from Formula Editor 3.0, the error message: "Microsoft Equation Editor not available" appears.

Microsoft has meanwhile published the support article 4057882 on the subject. It states that you should use the new equation editor from Office or the paid application MathType.

0patch brings back the equation editor 3.0, including patch

However, many users in science and research – or in companies – probably still have documents that can only be edited with the equation formula editor 3.0. The folks from opatch informed me by e-mail that they have developed a solution to the problem. There is a way to get the equation editor back. At the same time, opatch's micropatch technology can be used to close the known vulnerarbilities.

Whoever installed the Office security updates from January 9, 2018, has lost the equation editor 3.0. The respective updates delete five files (including EQNEDT32.EXE) from the EQUATION folder, leaving the subfolder 1033 and the EEINT.DLL in it intact. In addition, deleting CLSID {0002CE02-0000-0000-0000-0000-C000-0000000000000000000000000046} removes the Equation Editor from the registry as a local COM server.

However, in Office 2016, several files remain in the EQUATION folder after the update, and in some cases a 0-byte file EQNEDT32.EXE remains on the system.
The location of the EQUATION folder depends on both the Office version and whether the Office version is 32-bit or 64-bit. These are the default directories:

  • 32-bit Office 2007, 2010 and 2013 on 32-bit Windows: C:\Program Files\Common Files\microsoft shared\EQUATION
  • 32-bit Office 2007, 2010 and 2013 on 64-bit Windows: C:\Program Files (x86)\Common Files\microsoft shared\EQUATION
  • 64-bit Office 2007, 2010 and 2013: C:\Program Files\Common Files\Microsoft Shared\EQUATION
  • 32-bit Office 2016 and 365 on 32-bit Windows: C:\Program Files\Microsoft Office\root\VFS\ProgramFilesCommonX86\Microsoft Shared\EQUATION
  • 32-bit Office 2016 and 365 on 64-bit Windows: C:\Program Files (x86)\Microsoft Office\root\VFS\ProgramFilesCommonX86\Microsoft Shared\EQUATION
  • 64-bit Office 2016 and 365: C:\Program Files\Microsoft Office\root\VFS\ProgramFilesCommonX64\Microsoft Shared\EQUATION

You can copy the missing files from the Office installation media or another computer back to the appropriate folders. Afterwards, register the equation editor as a COM server again. And then you should install the 0patch fixes to close the vulnerarbility. opatch has published the exact description in this blog post. Maybe it will help the one or other user who depends on the formula editor 3.0.

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5 Responses to Reactivate Microsoft Office Equation Editor 3.0

  1. Herb Pynn says:

    I have 20 years of work invested in this equation editor 3.0 for microsoft office 2007
    I think. It stopped working this week of May 11-15, I need this to work on my files, I have tried my different things . Herb Pynn

  2. Somchart says:

    Thank you. It works.

  3. Світлана says:

    Дуже зручно і впевнено можно працювати у редакторі формул Microsoft Office Equation 3.0. Поверніть, його, будь ласка. Як на мене, новий редактор формул не зручний, просто дратує.

    It is very easy to use Microsoft Office Equation 3.0 formula editor. Could you please turn it back on? As for me, the new formula editor is not handy, just drab.

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  5. NonyaBiz says:

    These Microsoft sukers have finally disabled the eqnedt3.0 from running altogether in their she tee Windows 10. They can kiss my rear!

  6. Mahmmad-Taheri says:

    I cannot find download

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