Packages / @hono/node-server / Security
Node.js Adapter for Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)
Affected releases · @hono/node-server
- 2.x2.0.0 – 2.0.4Fixed in 2.0.5
- 1.x1.0.0 – 1.19.14Fixed in 1.19.15
- 0.6.x and older0.2.0 – 0.6.0No fix, no longer updated
On 2.x, the newest line:
npm install @hono/node-server@2.0.5Affected
2.0.0 – 2.0.4
5 releases
Fixed
2.0.5 – 2.1.5
13 releases, latest
Affected
1.0.0 – 1.19.14
72 releases
Fixed
1.19.15 – 1.19.17
2 releases
Affected
0.2.0 – 0.6.0
10 releases
Is your project affected?
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What happens
The same as the hono core Path traversal in serve-static on Windows via encoded backslash (%5C).
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.