Cisco recommends you stay with Cisco-supported patches and service releases in order to make sure your installation continues to be supported by TAC.
The release notes for OS service release 2.5sr2:
http://ftp.cisco.com/cisco/crypto/3DES/voice/cmva/win-OS-Upgrade-K9.2000-2-5sr2-Readme.htm
To quote, "The OS Service Releases started posting once a month on 9/1/2003. These monthly Service Releases will be created only if a new applicable security hotfix is available 5 business days before the 1st of the month. Cisco will continue to test and release hotfixes that meet our criteria for Critical hotfixes in 1 business day."
MS03-040 isn't all that critical considering that you shouldn't be using your CCM servers for general web browsing, much less browsing potentially hostile web sites. You should probably expect to see the fix rolled into OS service release 2.5sr3 to be released on or about November 1st.