PikiwiDB (Pika) v3.5.7 exposes an internal protobuf replication server on a port derived from the client port plus 2000 (e.g. 11221 when the default client port 9221 is used) that does not authenticate incoming requests. Although requirepass is intended to gate replication — a slave presents it as masterauth inside its MetaSync request — only the MetaSync handler (HandleMetaSyncRequest) validates it; the frame dispatcher (DealMessage) does not require a completed or attempted MetaSync before routing other message types to their handlers. As a result, an unauthenticated remote attacker can connect directly to the replication port and issue TrySync, DBSync, BinlogSync, and RemoveSlaveNode requests, obtaining the full-sync snapshot and live write stream and removing replica nodes, even when requirepass is configured.

PikiwiDB (Pika) v3.5.7 exposes an internal protobuf replication server on a port calculated as the client port plus 2000 (default: 11221) without authentication. While the requirepass configuration is meant to secure replication via masterauth in MetaSync requests, only the MetaSync handler validates credentials. The frame dispatcher DealMessage routes other message types without requiring prior authentication or MetaSync completion. An unauthenticated remote attacker can directly connect to the replication port and issue TrySync, DBSync, BinlogSync, and RemoveSlaveNode requests. This allows attackers to obtain full-sync snapshots, intercept live write streams, and remove replica nodes. The vulnerability persists even when requirepass is configured, rendering the authentication mechanism effectively bypassed for most replication operations.