Yes there is sectional cutoff in CAT and lack of performance in CAT sections can reduce you chances to get shortlisted in IIM's.

As per experts, its not the overall percentile but the sectional performance that matters and if the sections are performed well then automatically the overall percentile will be good.

Not all other bschools consider sectional cutoff that strictly and it may vary institute to institue.

You can check the sectional cut off weight age and ratings here in the link below:

IIM A

IIM B

IIM C

This will help you overall with the selection strategy as well.

Good Luck.