CVE-2026-54286: Honojs Hono

Medium severity, CVSS 5.9. EPSS: 0.4% chance of exploitation in the next 30 days.

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.

Affected products

• Honojs Hono: before 4.12.25 (fixed in 4.12.25)

Published 2026-06-22. Last modified 2026-06-23.