HTML Injection in Hono JSX Server-Side Rendering

Executive Summary

CVE-2026-56761 is an HTML injection vulnerability in the hono library versions before 4.12.14. It occurs during server-side rendering (SSR) of JSX when untrusted input is used as attribute names without proper validation.

Attackers can craft specially malformed attribute keys containing characters like quotes or angle brackets that break HTML tag boundaries, allowing them to inject unintended HTML attributes or elements into the rendered page.

This improper handling of JSX attribute names compromises the integrity of the generated HTML and can potentially lead to further security issues such as cross-site scripting (XSS) if combined with unsafe practices.

Useful 0 Not Useful 0

Impact Analysis

This vulnerability can impact you by allowing attackers to inject arbitrary HTML into your web pages during server-side rendering.

Such injection can break the structure of your HTML, potentially leading to security issues like cross-site scripting (XSS), which can compromise user data, session integrity, or the overall security of your web application.

Because the vulnerability arises from untrusted input being used as attribute keys without validation, it can be exploited remotely without requiring privileges or user interaction beyond visiting a crafted page.

Useful 0 Not Useful 0

Detection Guidance

This vulnerability arises from improper handling of JSX attribute names during server-side rendering in hono versions before 4.12.14, allowing HTML injection via malformed attribute keys.

To detect this vulnerability on your system, you should check the version of the hono library in use and inspect server-side rendering code that uses untrusted input as JSX attribute keys.

There are no specific detection commands provided in the available resources. However, general approaches include:

• Verify the hono package version by running: npm list hono
• Search your codebase for usage of JSX attribute keys that incorporate untrusted input, for example using grep or similar tools: grep -r 'attribute' ./src
• Monitor HTTP responses for unexpected or malformed HTML attributes that could indicate injection attempts.

Useful 0 Not Useful 0

Compliance Impact

The provided information does not specify any direct impact of the CVE-2026-56761 vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

Useful 0 Not Useful 0

Mitigation Strategies

To mitigate the CVE-2026-56761 vulnerability, you should upgrade the hono library to version 4.12.14 or later, where the issue with improper handling of JSX attribute names during server-side rendering has been fixed.

Additionally, avoid using untrusted input as JSX attribute keys during server-side rendering to prevent HTML injection.

Useful 0 Not Useful 0