Vulnerability Advisory : Echo: middleware.Static: `%2F`-encoded path bypasses route/group middleware guarding a statically-served path with LOW Attack Complexity

Echo is a Go web framework. Prior to 4.16.0 and 5.4.0, a globally mounted middleware.Static instance can interpret an encoded request path differently from Echo's router because the router matches the still-encoded path while the static handler uses the decoded URL.Path. The advisory demonstrates an encoded slash resolving to a file under the static root through the global static middleware, but the source is internally inconsistent about whether a route or group guard protects the corresponding literal path in that global-mount configuration. This issue is fixed in 4.16.0 and 5.4.0.