CVE-2026-39410 MEDIUM

CVE-2026-39410: Hono has a non-breaking space prefix bypass in cookie name handling in getCookie()

Vendor Honojs
Product hono
Weakness CWE-20 · Input validation
Published April 8, 2026
Last update April 8, 2026

CVSS base score

4.8/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality Low
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

What the vulnerability does

01Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.12, a discrepancy between browser cookie parsing and parse() handling allows cookie prefix protections to be bypassed. Cookie names that are treated as distinct by the browser may be normalized to the same key by parse(), allowing attacker-controlled cookies to override legitimate ones. This vulnerability is fixed in 4.12.12.

Key dates

02Disclosure timeline

April 8, 2026 CVE published
April 8, 2026 Record updated