---
id: GHSA-frvp-7c67-39w9
title: >-
  Node.js Adapter for Hono: Path traversal in `serve-static` on Windows via
  encoded backslash (`%5C`)
summary: >-
  Node.js Adapter for Hono: Path traversal in `serve-static` on Windows via
  encoded backslash (`%5C`)
severity: medium
cvss: 5.9
cwe:
  - CWE-22
vendor: hono
product: '@hono/node-server'
ecosystem: npm
affected:
  - '@hono/node-server < 2.0.5'
patched:
  - '@hono/node-server 2.0.5'
published: '2026-07-21'
updated: '2026-07-21'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-frvp-7c67-39w9'
references:
  - url: >-
      https://github.com/honojs/node-server/security/advisories/GHSA-frvp-7c67-39w9
  - url: >-
      https://github.com/honojs/node-server/commit/cd076e117cfe4cb8d31f9eb11d2e8f38a6cb8faf
  - url: 'https://github.com/honojs/node-server/releases/tag/v2.0.5'
  - url: 'https://github.com/advisories/GHSA-frvp-7c67-39w9'
tags:
  - ghsa
  - npm
ingestedAt: '2026-07-21T18:53:06.739Z'
---

## Overview

The same as the `hono` core [Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)](https://github.com/honojs/hono/security/advisories/GHSA-wwfh-h76j-fc44).

### Summary

On Windows hosts, an encoded backslash (`%5C`) in the request path decodes to `\`, which the Windows path resolver treats as a separator. `serve-static` then resolves a single URL segment such as `admin\secret.txt` into a nested file under the root and serves it, letting an attacker read static files meant to be protected behind prefix-mounted middleware. Directory escape (`..`) remains blocked.

### Details

The router splits paths only on `/`, so `/admin%5Csecret.txt` is one segment and middleware on `/admin/*` does not run. The `serve-static` guard rejects `.`/`..` and consecutive separators but lets a lone `\` through; on Windows the file resolver re-splits it into the protected subtree.

This affects Windows hosts serving static files via the Node, Bun, or Deno adapters that guard a static subtree with prefix-mounted middleware.

### Impact

An unauthenticated attacker can read static files under a middleware-guarded prefix on Windows hosts. The read stays within the configured root; escape outside the root is not possible.

## Affected packages

- `@hono/node-server < 2.0.5`

## Remediation

Upgrade to a patched release:

- `@hono/node-server 2.0.5`