PT-2026-56505 · Hono · Hono

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CVE-2026-59895

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Published

2026-07-08

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Updated

2026-07-21

CVSS v3.1

6.1

Medium

VectorAV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Name of the Vulnerable Software and Affected Versions Hono versions 4.0.0 through 4.12.26
Description The cx() function in hono/css composes class names from plain strings but marks the result as already escaped without performing HTML-escaping on the input. This allows untrusted className values used in a JSX class attribute during server-side rendering to break out of the attribute and inject arbitrary markup.
Recommendations Update to version 4.12.27.

Exploit

Fix

XSS

Improper Encoding or Escaping of Output

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Weakness Enumeration

Related Identifiers

CVE-2026-59895
GHSA-W62V-XXXG-MG59

Affected Products

Hono