Hono: `serveStatic` decodes the request path a second time, leading to bypass of middleware on static paths

Overview

Hono is a Web application framework that provides support for any JavaScript runtime. From 4.12.4 until 4.13.11, serveStatic can interpret a malformed percent-encoded path differently from upstream routing middleware and bypass protection for a static prefix. The root cause is serveStatic decodes a routed request path a second time before filesystem lookup. The attack mechanism is malformed percent encoding survives the first routing interpretation and becomes a protected path only during the later static-file decode. The affected component is serveStatic. The trigger conditions are an application protects a static prefix with upstream middleware and serveStatic receives an attacker-controlled malformed percent-encoded path. The impact is unauthorized disclosure of a static file that upstream middleware was intended to protect. The issue does not permit traversal outside the configured static root. This issue is fixed in version 4.13.11.

Affected

• hono >= 4.12.4, < 4.13.11

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.