CVE-2026-39406: hono node-server Path Traversal

Vulnerability summary

CVE-2026-39406 is a medium (CVSS 5.3) Path Traversal vulnerability in hono node-server. EPSS estimates a 0.40% chance of exploitation in the next 30 days, higher than 32.8% of scored vulnerabilities.

Timeline

1. 08-04-2026
   PublishedVulnerability first disclosed.
2. 08-04-2026
   Last modifiedVulnerability information updated.

Description

@hono/node-server allows running the Hono application on Node.js. Prior to 1.19.13, a path handling inconsistency in serveStatic allows protected static files to be accessed by using repeated slashes (//) in the request path. When route-based middleware (e.g., /admin/*) is used for authorization, the router may not match paths containing repeated slashes, while serveStatic resolves them as normalized paths. This can lead to a middleware bypass. This vulnerability is fixed in 1.19.13.

• CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.