CVE-2026-54286 PUBLISHED

Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)

Assigner: GitHub_M
Reserved: 12.06.2026 Published: 22.06.2026 Updated: 23.06.2026

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, 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. This vulnerability is fixed in 4.12.25.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS Score: 5.9

Product Status

Vendor honojs
Product hono
Versions
  • Version < 4.12.25 is affected

References

Problem Types

  • CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') CWE