@grpc/grpc-js implements the core functionality of gRPC purely in JavaScript, without a C++ addon. Prior to 1.13.1 and 1.14.1, the exact path (method name) matcher used by RBAC performs a prefix comparison instead of an equality comparison when case-insensitive matching is enabled. If one service method name prefixes another and the methods have different access rules, a request for the longer method can match the shorter methods rule and cause incorrect authorization. This issue is fixed in versions 1.13.1 and 1.14.1.
The product performs a comparison that only examines a portion of a factor before determining whether there is a match, such as a substring, leading to resultant weaknesses.