medium6.1
CVE-2026-59895
Hono is a Web application framework that provides support for any JavaScript runtime.
Impact
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 packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | hono | >= 4.0.0, < 4.12.27 | 4.12.27 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Hono | Hono | from 4.0.0 before 4.12.27 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-w62v-xxxg-mg59
- https://github.com/honojs/hono/security/advisories/GHSA-w62v-xxxg-mg59
- https://nvd.nist.gov/vuln/detail/CVE-2026-59895
- https://github.com/honojs/hono/commit/cd3f6f7194f0e5c9d4b26ae0cf232018d0f388fc
- https://github.com/honojs/hono/releases/tag/v4.12.27