[It is important that you do not launch the game through Steam for the time being, as doing so will "update" your client backwards to 1.6 again.]

TL;DR
Activision updated CoD4 backwards from 1.7 to 1.6
For Steam users, this "update" is forced when launching the game, and they cannot connect to 1.7 servers.
The exploit fixed by this "update" does not affect CoD4, it is fine to run the 1.7 binary, which can be found in our Downloads section, and is also attached to this post:

• https://fhclan.com/forum/index.php?action=downloads;sa=view;down=16

After replacing the binary, do not launch the game through Steam, as this will cause the game to "update" backwards to 1.6 again.


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Earlier today, Activision pushed an iw3mp.exe binary "update": support.activision.com

Since the latest version of CoD4 has been 1.7 since 2008, this is naturally causing confusion, and for people that use digital installs like Steam, is creating problems finding servers to connect to. Steam distributes the game in the manner the publisher distributes it to them, so launching CoD4 with Steam now will "update" the game from version 1.7 to version 1.6

Unfortunately, since nearly all servers are now running 1.7, 1.7a, or CoD4x (1.8), this creates a version mismatch and the client will no longer allow you to connect to your favorite servers!

If you read the link to the Activision article above, you saw that this is supposedly a security update. It is unclear what the patch fixes, but there is speculation that it is to address a RCE (Remote Code Execution) exploit: https://www.reddit.com/r/CallOfDuty/comments/88l1ss/mw2_severe_security_exploit_in_mw2_pc_remote/

Interestingly, the exploit in question only affects PvP versions of the game, where details about all of the lobby clients (IP addresses, port numbers, etc) are shared with every client. The PC version of CoD4 utilizes dedicated servers, and therefore this is not an issue. Developers of the CoD4x patch have also confirmed that CoD4 is unaffected: COD4 Steam Update - Cod4 - CoD4X Mod Community

That said, getting your client back to 1.7 version of CoD4 will allow you to connect to you to connect to your favorite servers again! The 1.6 to 1.7 patch does not work, but since this 1.6 update did not change any of the scripts for the game, simply replacing the binary will do the trick.

• Download the iw3mp.exe binary
• Verify the checksum(s)
• Copy the executable binary into your CoD4 directory, overwriting the 1.6 binary. For Steam, this is usually
  C:\Program Files (x86)\Steam\steamapps\common\call of duty 4
• Launch the game by double clicking the executable, or by making a new shortcut to the 1.7 binary and launching with the shortcut.

It is important that you do not launch the game through Steam for the time being, as doing so will "update" your client backwards to 1.6 again.

iw3mp.exe checksums

• MD5: 8c40cde102a9d8297a8674cb149f96ed
• SHA1: 3323b3882f9465a4c66cf298833435150effb153
• SHA256: e41fcd5921dfdcb8c71a76a605f71df4b5f6a525b5859e590e2dd9645f1fa893

Thanks for posting this.  I had run into this issue earlier this afternoon, and spent about an hour wrestling with this before I spotted the iw3mp.exe client was downgraded to v1.6.  After restoring the file from backup, I was up and running again, and saw an opportunity to upgrade...and am now running v1.8-17.7!  Oh well...it works.

after downloading the iw3mp, I got this error message: The code execution cannot proceed because binkw32.dll was not found reinstalling the program may fix this problem. what does it mean and how do I fix it? ty

after downloading the iw3mp, I got this error message: The code execution cannot proceed because binkw32.dll was not found reinstalling the program may fix this problem. what does it mean and how do I fix it? ty

Did you reboot your pc ?

no that message appeared almost immediately after i tried to download.

no that message appeared almost immediately after i tried to download.

That error appeared almost immediately after you downloaded, as in you clicked download and then the error popped up before you could do anything else?

That error message appeared as soon as I clicked on the download, and that was the end of that.

Your browser may be configured to automatically run executable downloads. If that's the case, the iw3mp.exe is in your C:\Users\<Username>\Downloads folder. You can check to make sure it downloaded properly:

Navigate to the Downloads folder, and if iw3mp.exe is present, hold down SHIFT and right-click in the white space. One of the options in the menu will be Open command window here, choose that option. If that option is not present, you did not hold down shift.
Now, you'll have a command prompt with a working directory inside your Downloads folder. You can now use Microsoft's builtin certutil to verify the file:

Code Select Expand

certutil  -hashfile "iw3mp.exe" SHA256
Running this should return the following:

Code Select Expand

SHA256 hash of the file iw3mp.exe:
e4 1f cd 59 21 df dc b8 c7 1a 76 a6 05 f7 1d f4 b5 f6 a5 25 b5 85 9e 59 0e 2d d9 64 5f 1f a8 93
CertUtil: -hashfile command completed successfully.


If the hash matches, the file download is okay, continue with the steps outlined above (copy the binary into your CoD4 directory and overwrite the 1.6 version of iw3mp.exe).

If that hash does not match, the file is corrupt, delete the iw3mp.exe, and try to download it again. I would recommend trying the download in a different browser. If you used Internet Explorer, try it with Chrome or Firefox. Verify the file checksum again, and then continue to overwrite the version 1.6 iw3mp.exe

ok Pear will try that! hope I can get it to work! thanks

pear the checksums match!, but I dont have a clue on how to overwrite 1.6 exc!

Simply drag the downloaded file into the folder that has iw3mp.exe and replace the old .exe with your new .exe because that folder has the binkw32.dll file already. After you have replaced the .exe file then right click and create a shortcut to your desktop, then open the shortcut to play, do not open cod from your steam app or it will update to 1.6 again

Simply drag the downloaded file into the folder that has iw3mp.exe and replace the old .exe with your new .exe

This.

As outlined above, the path for the old .exe is usually C:\Program Files (x86)\Steam\steamapps\common\call of duty 4
This is the default path for Steam games, the only way this will change is if you have modified your setup.



You'll see the iw3mp.exe there, which is version 1.6. Like zMan said, just drag and drop the 1.7 executable into that window. You'll get a prompt warning you that There is already a file with the same name in this location. Choose the first option, usually titled Copy and Replace or Move and Replace. This will replace the file in the destination folder with the file you are moving/copying (iw3mp.exe version 1.7).

I'm sorry but as  I still am not allowed to download the iw3mp.exc because of the error message described earlier nothing matters after that. if someone can tell me how to get around that problem maybe I can do as you say. thanks

I am oldschool and use a cd version..... I don't use Steam at all.

That's how I solved my problem! got the CD and and got rid of steam!