CVE-2026-29045: Hono

Critical severity, CVSS 9.8. EPSS: 0.6% chance of exploitation in the next 30 days.

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to version 4.12.4, when using serveStatic together with route-based middleware protections (e.g. app.use('/admin/*', ...)), inconsistent URL decoding allowed protected static resources to be accessed without authorization. The router used decodeURI, while serveStatic used decodeURIComponent. This mismatch allowed paths containing encoded slashes (%2F) to bypass middleware protections while still resolving to the intended filesystem path. This issue has been patched in version 4.12.4.

Affected products

• Hono Hono: before 4.12.4 (fixed in 4.12.4)

Published 2026-03-04. Last modified 2026-06-17.