CVE-2026-59895
Medium
Description
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.
SeverityMedium
CVSS6.1
Exploit probability—
Product
Hono
PublishedJul 8, 2026
First seenJul 8, 2026
Weakness typeCWE-79Cross-site scripting (XSS)CWE-116CWE-116
How to fix
Update
- hono hono4.12.27 or later
- hono4.12.27 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| hono hono | 4.0.0 ≤ v < 4.12.27 | 4.12.27 |
| hononpm | 4.0.0 ≤ v < 4.12.27 | 4.12.27 |
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