Block List (Blacklist)

Also: Block list, Blocklist, Deny list

PCIComplianceHub · Last updated 22 September 2026

A list of entities, such as IP addresses, domains or applications, that are denied access to a system because they are known or suspected to be malicious. Block lists are reactive: anything not listed is permitted, so they cannot catch a threat that has not been seen before. Block list and allow list are the current terms; the older blacklist and whitelist wording is being retired across the industry and in PCI SSC documentation.