A Trailing Slash Bypassed AWS API Gateway Authorization (opens in new tab)

A security researcher found that adding a trailing slash to AWS HTTP API paths bypassed Lambda authorizer authentication entirely, enabling unauthenticated wire transfers at a fintech. The root cause is a path normalization mismatch between HTTP API's greedy route matching and its authorization layer. The same vulnerability class appeared in gRPC-Go via CVE-2026-33186.