PT-2026-49733 · Npm · Hono
Published
2026-06-16
·
Updated
2026-06-16
·
CVE-2026-54286
CVSS v3.1
5.9
Medium
| Vector | AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |
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 adminsecret.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.
Fix
Path traversal
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Weakness Enumeration
Related Identifiers
Affected Products
Hono