When using @hono/node-server's static file serving together with route-based middleware protections (e.g. protecting /admin/*), inconsistent URL decoding can allow protected static resources to be accessed without authorization.
In particular, paths containing encoded slashes (%2F) may be evaluated differently by routing/middleware matching versus static file path resolution, enabling a bypass where middleware does not run but the static file is still served.
// detailsThe routing layer and the node-server static handler normalize request paths differently. The router preserves %2F as a literal string when matching routes, while the static handler decodes %2F into / before resolving the filesystem path.
Example request:
- /admin%2Fsecret.html
This may:
- fail to match middleware intended for /admin/*, but
- still be resolved by the static handler as /admin/secret.html under the configured static root.
This does not allow access outside the configured static root and is not a path traversal vulnerability.
// impactAn unauthenticated attacker could bypass route-based authorization protections for protected static resources by supplying paths containing encoded slashes.
Applications relying solely on route-based middleware to protect static subpaths under the same static root may have exposed those resources.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None