---
id: CVE-2026-56763
title: >-
  Hono before 4.12.7 allows __proto__ key in parseBody with dot option enabled,
  permitting specially crafted form field names to create objects with __proto__
  properties
summary: >-
  Hono before 4.12.7 allows __proto__ key in parseBody with dot option enabled,
  permitting specially crafted form field names to create objects with __proto__
  properties. When parsed results are merged into regular JavaScript objects
  using…
severity: medium
cvss: 4.8
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N'
cwe:
  - CWE-1321
published: '2026-07-11'
updated: '2026-07-11'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-56763'
references:
  - url: 'https://github.com/honojs/hono/security/advisories/GHSA-v8w9-8mx6-g223'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/hono-prototype-pollution-via-proto-key-in-parsebody-with-dot-option
    label: disclosure@vulncheck.com
tags:
  - nvd
ingestedAt: '2026-07-11T23:16:21.066Z'
epss: 0.00273
epssPercentile: 0.17567
---

## Overview

Hono before 4.12.7 allows __proto__ key in parseBody with dot option enabled, permitting specially crafted form field names to create objects with __proto__ properties. When parsed results are merged into regular JavaScript objects using unsafe merge patterns, attackers can exploit this to achieve prototype pollution and modify object behavior.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.