inform to project manager

if any of the project is in support or maintaince phase, 
Before loggin the defect ( mostly critical or high ) check 
with your test Manager and before, check how its going to 
impact on the application.

As you told its already 6 year before so i don't think so 
client is facing any critical issue on this. Anyway better 
to discuss with your test manager and if possible check 
with your BA and if it is necessary to fix dis issues or we 
may fix it later point of time during CR's ( Change 
Request ).