CVE-2026-56763

Medium

Description

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.

SeverityMedium

CVSS4.8

Exploit probability—

Product

Hono

PublishedJul 11, 2026

First seenJul 11, 2026

Weakness typeCWE-1321Prototype pollution

How to fix

Update

hono4.12.7 or later

Vendor advisories

github.com/honojs/hono/security/advisories/GHSA-v8w9-8mx6-g223

Affected products

Product	Affected versions	Fixed in
hononpm	v < 4.12.7	4.12.7

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