The Kademlia DHT (go-libp2p-kad-dht 0.20.0 and earlier) used in IPFS (0.18.1 and earlier) assigns routing information for content (i.e., information about who holds the content) to be stored by peers whose peer IDs have a small DHT distance from the content ID. This allows an attacker to censor content by generating many Sybil peers whose peer IDs have a small distance from the content ID, thus hijacking the content resolution process.

Content Censorship in the InterPlanetary File System (IPFS) via Kademlia DHT abuse