Yes, a student can appear in CAT exam with a backlog.

• You just need to select “Yes” to the question registration form that asks: Are you in the final year of Bachelor’s Degree?”
• The only rule that exists here is you have to score 50%
• The certificate from your issuing university should be submitted before June 2017. Or you can submit a certificate issued by the Principal/Registrar of University before June 30, 2017 – that would certify you as you have taken the supplementary examination and the results are awaited.
• Candidates belonging to Reserved Category have to submit a copy of the certificate while registering , without which the registration will fail.