Vulnerability · Published Apr 8, 2026 · Assigned by GitHub_M

CVE-2026-39407Hono has a middleware bypass via repeated slashes in serveStatic

Medium 5.3

In plain English

A medium-severity path traversal in hono from honojs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)0.5%top 59.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	hono	4.12.12	GHSA-wmmm-f939-6g9c

Affected products (as reported)

Vendor	Product	Versions
honojs	hono	< 4.12.12

Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

References

https://github.com/honojs/hono/security/advisories/GHSA-wmmm-f939-6g9c x_refsource_CONFIRM
https://github.com/honojs/hono/commit/9aff14bd727f8b0435c963363fd803260e7b8e3c x_refsource_MISC
https://github.com/honojs/hono/releases/tag/v4.12.12 x_refsource_MISC