I have some old application in ColdFusion 5 connecting to Oracle 9 and SQL. We have upgraded to Oracle 11 making it incompatibel. Is upgrading to ColdFusion 11 an option? Are there known issues and challenges?
First, check to see if anyone (trusted) has drivers for CF5 and Oracle 11. Doubtful, but you never know.
Second, I hate to say it, but you should have been gradually upgrading things instead of waiting for so long. There is such a huge difference between CF5 and CF11 (deprecated tags, etc.) that I do believe there is no migration tool for it. Your best bet is to do a fresh install of CF10 or CF11 (heck.. I think even CF9 should have Oracle 11 drivers available), copy your .cfm/.cfc files to it, and go through each file, updating the code as you go along. I know it will be tedious and time-consuming, but (not trying to sound like a jerk) you have no one to blame but yourself (or your IT dept) for not keeping up.
I sincerely hope you find a viable solution.
When we migrated from CF5 to CF9 most of our headache revolved around some custom CFX tags we were using as these did not play nicely with Java. Other than our own CFX caused headaches the CF compatibility issues were few and minor. Since then, CF9 to 11 compatibility issues are all but non-existent. I don't know the requirement of your site in particular but the chances are good that your site will run without or maybe very minor issues. Test! Test!! Test!!!