Remote crash via unchecked skip-index overflow

Improper bounds checking in GoGo Protobuf before 1.3.2 allows remote attackers to crash dependent applications with crafted messages. Generated Unmarshal methods add an attacker-controlled skip length to the current index without rejecting integer overflow, allowing a negative result to reach slice operations and trigger an out-of-bounds panic. Exposure requires an application generated with the vulnerable unmarshaler to parse protobuf messages from an untrusted remote party; the bounded consequence is process termination and service interruption.