hono Improperly Handles JSX Attribute Names Allows HTML Injection in hono/jsx SSR

## Summary Improper handling of JSX attribute names in hono/jsx allows malformed attribute keys to corrupt the generated HTML output. When untrusted input is used as attribute keys during server-side rendering, specially crafted keys can break out of attribute or tag boundaries and inject unintended HTML. ## Details When rendering JSX elements to HTML strings, attribute values are escaped, but attribute names (keys) were previously inserted into the output without validation. If an attribute name contains characters such as `"`, `>`, or whitespace, it can alter the structure of the generated HTML. For example, malformed attribute names can: * Break out of the current attribute and introduce unintended additional attributes * Break out of the current HTML tag and inject new elements into the output This issue arises when untrusted input (such as query parameters or form data) is used as JSX attribute keys during server-side rendering. ## Impact An attacker who can control attribute keys used in JSX rendering may inject unintended attributes or HTML elements into the generated output. This may lead to: * Injection of unexpected HTML attributes * Corruption of the HTML structure * Potential cross-site scripting (XSS) if combined with unsafe usage patterns This issue affects applications that pass untrusted input as JSX attribute keys during server-side rendering.

Source published

16 Apr 2026 01:02:24 UTC

Source modified

10 Sep 2026 03:50:42 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Publisher rating · MODERATE