CVE-2026-39410: Hono

Medium severity, CVSS 4.8. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Hono Hono: up to and including 4.12.11

Published 2026-04-08. Last modified 2026-07-24.