CVE-2026-59895: Hono

Medium severity, CVSS 6.1. EPSS: 0.3% chance of exploitation in the next 30 days.

Hono is a Web application framework that provides support for any JavaScript runtime. From 4.0.0 before 4.12.27, cx() in hono/css composes class names from plain strings but marks the result as already escaped without HTML-escaping the input, allowing untrusted className values used in a JSX class attribute during server-side rendering to break out of the attribute and inject arbitrary markup. This issue is fixed in version 4.12.27.

Affected products

• Hono Hono: from 4.0.0, before 4.12.27 (fixed in 4.12.27)

Published 2026-07-08. Last modified 2026-07-10.