Logstash CIDR network range

Hello,

How to match IP range which is not full network range?
Example: 172.20.23.5 in [172.16.0.0 -172.31.255.255 ]

CIDR filter plugin specifies the full range but I need to search is specific range.

Sounds like you want to match against 172.16.0.0/12. What is stopping you doing that using a cidr filter?