Path Traversal in Hono

CVE-2026-39407

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.12, 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 4.12.12.

Vulnerability class: Path Traversal (Directory Traversal)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.004 (36.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 36.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-39407: held from 0.005 to 0.004.

EPSS over last 30 days · oldest: 0.005 · newest: 0.004 · change: -0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-39407?
CVE-2026-39407 is a medium-severity vulnerability in Hono, classified under Path Traversal. CVSS score: 5.3/10. Published 2026-04-08.
How severe is CVE-2026-39407?
Medium severity. CVSS v3 base score is 5.3 out of 10.