Hono: `mount()` and `app.mount()` can forward a path that bypasses middleware scoped inside the mount prefix

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-126357
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-13 00:20:10 UTC
Updated2026-11-13 00:20:11 UTC
DescriptionHono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.13.16, mount() and app.mount() can remove a dynamic mount prefix using the route-pattern length rather than the matched-prefix length, allowing a crafted path to be forwarded as a protected inner route while the outer application routes the original path. Since 4.12.21, rebuilding the forwarded URL from the decoded pathname can also convert a decoded backslash to a slash and collapse parent-directory segments, again causing the mounted application to receive a protected path. An unauthenticated client can use either applicable path transformation to reach a mounted route without authentication or authorization middleware scoped to a subpath inside the mount prefix. This issue is fixed in version 4.13.16.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Problem Types: CWE-288 | CWE-288 CWE-288: Authentication Bypass Using an Alternate Path or Channel

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Honojs Hono affected < 4.13.16 Not specified

References

ReferenceSourceLinkTags
github.com/honojs/hono/releases/tag/v4.13.16 [email protected] github.com
github.com/honojs/hono/commit/34f90432a1794b28e52802670efcd01963f716d6 [email protected] github.com
github.com/honojs/hono/security/advisories/GHSA-4m76-xfj5-7975 [email protected] github.com
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