It's possible to recover the security, admin and app passwords on a CUCM (or other UCOS host) as opposed to resetting them. If running on VMWare, take a snapshot just in case. Boot the UCOS host using a Linux rescue CD and extract this file...
and copy to your server. An alternative that doesn't involve downtime is to issue the command:
utils create report platform
Then follow the instructions to upload to an SFTP server.
You can then use the UCOS Password Decrypter app to open the file. It will show you the decrypted passwords. You can download it here...
This way you don't go through the headache of resetting the cluster security password on your pub & subs. To perform the actual copy of the XML file to a Windows host, I boot the UCOS host with a CentOS Live ISO, configure a temp static IP then start the SSHD service. From there I use WinSCP on my Windows box to connect to the CentOS live session and extract the file.