CVE-2026-59895
MEDIUMHono: Server-Side XSS via JSX Escaping Bypass in cx() Utility
Title source: cnaDescription
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.
References (3)
Core 3
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/honojs/hono/security/advisories/GHSA-w62v-xxxg-mg59
X_Refsource_Misc x_refsource_misc
https://github.com/honojs/hono/commit/cd3f6f7194f0e5c9d4b26ae0cf232018d0f388fc
X_Refsource_Misc x_refsource_misc
https://github.com/honojs/hono/releases/tag/v4.12.27
Scores
CVSS v3
6.1
EPSS
0.0020
EPSS Percentile
9.9%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
partial
Details
CWE
CWE-116
CWE-79
Status
published
Products (3)
hono/hono
4.0.0 - 4.12.27
honojs/hono
>= 4.0.0, < 4.12.27
npm/hono
4.0.0 - 4.12.27npm
Published
Jul 08, 2026
Tracked Since
Jul 08, 2026