---
id: CVE-2026-47675
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, the serialize() function in hono/cookie validates
  domain and path options against characters that corrupt Set-Cookie header
  syntax (;…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N'
cwe:
  - CWE-113
  - CWE-1287
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-2026-47675'
references:
  - url: 'https://github.com/honojs/hono/security/advisories/GHSA-3hrh-pfw6-9m5x'
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00279
epssPercentile: 0.18972
ingestedAt: '2026-10-14T20:53:12.340Z'
---

## Overview

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, the serialize() function in hono/cookie validates domain and path options against characters that corrupt Set-Cookie header syntax (;, \r, \n), but does not apply the same validation to sameSite and priority. An application that passes user-controlled input into either option may produce a Set-Cookie response header containing attacker-chosen additional attributes. This vulnerability is fixed in 4.12.21.

## Affected

- `hono < 4.12.21`

## Remediation

Upgrade past the affected range:

- `hono 4.12.21`