GHSA-wcpc-wj8m-hjx6

## Summary

protobufjs could recurse without a depth limit while converting decoded messages to plain objects or JSON. This affected generated `toObject()` conversion and the custom `google.protobuf.Any` JSON conversion path.

A crafted protobuf binary payload containing deeply nested `Any` values could cause the JavaScript call stack to be exhausted during conversion to JSON.

## Impact

An attacker who can provide protobuf binary data decoded by an application may be able to crash the process or otherwise cause message conversion to fail with a stack overflow.

This affects applications that decode untrusted protobuf input containing `google.protobuf.Any` values and then convert decoded messages to JSON or plain objects with JSON conversion enabled, for example through `JSON.stringify(message)`, `Message#toJSON()`, or `Type.toObject(message, { json: true })`.

Applications that only decode and re-encode protobuf binary data without converting decoded messages to JSON are not directly affected by this issue.

## Preconditions

* The application must decode protobuf binary data influenced by an attacker. * The application schema must include `google.protobuf.Any`, and the referenced `type_url` must resolve to a message type in the loaded protobuf root. * The application must convert the decoded message to JSON or a plain object through an affected conversion path. * The crafted input must contain deeply nested `Any` values that are expanded during conversion.

## Workarounds

Avoid converting untrusted protobuf messages containing `google.protobuf.Any` values to JSON with affected versions. If immediate upgrade is not possible, reject or limit messages with deeply nested `Any` payloads at an outer protocol boundary where feasible, avoid JSON conversion of untrusted `Any` values, or isolate message conversion in a process that can be safely restarted.