---
id: CVE-2026-47676
title: >-
  Hono is a Web application framework that provides support for any JavaScript
  runtime
summary: >-
  Hono is a Web application framework that provides support for any JavaScript
  runtime. Prior to 4.12.21, app.mount() strips the mount prefix from the
  incoming request path using the raw URL pathname, while route matching is
  performed agai…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-444
  - CWE-693
vendor: hono
product: hono
affected:
  - hono < 4.12.21
patched:
  - hono 4.12.21
published: '2026-05-28'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T20:10:00.190'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-47676'
references:
  - url: 'https://github.com/honojs/hono/security/advisories/GHSA-2gcr-mfcq-wcc3'
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.0033
epssPercentile: 0.24428
ingestedAt: '2026-10-14T20:53:12.341Z'
---

## Overview

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, app.mount() strips the mount prefix from the incoming request path using the raw URL pathname, while route matching is performed against the percent-decoded path. This inconsistency causes the prefix to be stripped at the wrong position when the path contains percent-encoded multi-byte characters, resulting in the mounted sub-application receiving an incorrect path. This vulnerability is fixed in 4.12.21.

## Affected

- `hono < 4.12.21`

## Remediation

Upgrade past the affected range:

- `hono 4.12.21`