Protocol Buffers, or protobuf, is a compact binary serialization format used to exchange structured messages between systems. Instead of sending verbose text like JSON, applications encode data into a schema-defined message layout that is smaller and faster to parse. That makes protobuf popular in APIs, microservices, and remote procedure call systems where performance matters.
In cyber security, protobuf matters because parsers often process attacker-controlled input. A bug in decoding logic can turn a tiny message into a resource-exhaustion attack, especially when fields drive large allocations, recursion, or expensive handling of unknown fields. That can produce denial of service even in memory-safe languages. Defenders reduce risk by validating message sizes, setting parser budgets, fuzzing decoders, and using static analysis to find unsafe data flows before release.