Hono 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.
Metrics
Affected Vendors & Products
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Advisories
| Source | ID | Title |
|---|---|---|
 Github GHSA |
GHSA-4m76-xfj5-7975 | Hono: `mount()` and `app.mount()` can forward a path that bypasses middleware scoped inside the mount prefix |
Fixes
Solution
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Workaround
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References
History
Thu, 12 Nov 2026 22:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Hono 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. | |
| Title | Hono: `mount()` and `app.mount()` can forward a path that bypasses middleware scoped inside the mount prefix | |
| Weaknesses | CWE-288 | |
| References |
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| Metrics |
cvssV3_1
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Projects
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MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-11-12T22:18:46.437Z
Reserved: 2026-11-10T21:12:01.227Z
Link: CVE-2026-126357
Vulnrichment
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NVD
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Redhat
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OpenCVE Enrichment
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Weaknesses