12.3 1a <-- this version hasn't been in the Fixed-Series in advisiory.

But it's completed immume with the above Bugs.

I've tested it with my own lab.
My DoS program was written in Java, sending multiple packets with protocol fiend 109 to the Router.

12.3 1a was complie in 1-6-2003 for 2500
The 2500 series has been EOL and EOS very long time ago, still Cisco release the new version, this question if Cisco has known this bugs for long, at least before 1-6-2003. So i guess the impact won't be messy.