Hello dear aspirant

Hope you’re doing well

For CDS exam there is no fixed percentage, you just need to be a graduate and of course you need to pass the the CDS exam.

Other eligibility criteria is

candidates willing to appear for CDS should be graduates and between the age group of 19 to 25 years.

To see the details of CDS exam, eligibility criteria, etc

Kindly refer to the below attached link

https://www.google.co.in/amp/s/competition.careers360.com/articles/cds-eligibility-criteria/amp

Hope this helps

Good luck