Nasty Memory Leak In CUCM 12.5 (SU1)

Are you on Cisco unified communications manager version 12.5 (SU1)? If you are, you may soon run into a memory leak that one of my clients hit just last week. This memory leak has severe implications for Cisco Jabber.


As indicated above, this bug is fixed in Cisco’s 12.5 (SU2) release. The bug itself centers around Jabber.


  • You are running CUCM 12.5 or 12.5 (SU1)
  • The Tomcat service is receiving 10+ requests per second (Jabber, Web Interface, Other Log In)


  • Cisco Tomcat service becomes unresponsive
    • Cisco Jabber becomes unresponsive
    • No Web Access
    • Cannot log in to other apps including Extension Mobility

This bug is particularly difficult to deal with. That is because nothing is going to bring your server back other than patience… And that can be a difficult thing to identify when you’re in the heat of troubleshooting. For us, it took all day for Jabber clients to slowly get back online… This made the troubleshooting ever more confusing! The problem was gradually fixing itself?

Ideally, based on what I indicated above, stagger your jabber logins. If you can, restrict parts of the network so that you don’t get so many at once. Then, restart your Tomcat Service and you should be good to go.

Oh, and remember, upgrade your CUCM at the nearest opportunity. We can help with that:

A few notes to close on…

  • Restarting your server can cause the requests to your tomcat to spike, triggering the bug during troubleshooting.
  • Cisco notes that the bug can be triggered with fewer requests over a longer period of time.

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Not on CUCM 12.5? We wrote a post on the benefits of upgrading.