CVE-2026-39409: Hono

Medium severity, CVSS 5.3. EPSS: 0.4% 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, ipRestriction() does not canonicalize IPv4-mapped IPv6 client addresses (e.g. ::ffff:127.0.0.1) before applying IPv4 allow or deny rules. In environments such as Node.js dual-stack, this can cause IPv4 rules to fail to match, leading to unintended authorization behavior. 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.