CVE-2026-24771: Hono has a Cross-site Scripting vulnerability
Summary
A Cross-Site Scripting (XSS) vulnerability exists in the ErrorBoundary component of the hono/jsx library. Under certain usage patterns, untrusted user-controlled strings may be rendered as raw HTML, allowing arbitrary script execution in the victim's browser.
Details
The issue is in the ErrorBoundary component (src/jsx/components.ts). ErrorBoundary previously forced certain rendered output paths to be treated as raw HTML, bypassing the library's default escaping behavior. This could result in unescaped rendering when developers pass user-controlled strings directly as children, or when fallbackRender returns user-controlled strings (for example, reflecting error messages that contain attacker input).
This vulnerability is only exploitable when an application renders untrusted user input within ErrorBoundary without appropriate escaping or sanitization.
Impact
Successful exploitation may allow attackers to execute arbitrary JavaScript in the victim’s browser (reflected XSS). Depending on the application context, this can lead to actions such as session compromise, data exfiltration, or performing unauthorized actions as the victim.
Affected Components
hono/jsx: ErrorBoundary component
Other sources
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to version 4.11.7, a Cross-Site Scripting (XSS) vulnerability exists in the ErrorBoundary component of the hono/jsx library. Under certain usage patterns, untrusted user-controlled strings may be rendered as raw HTML, allowing arbitrary script execution in the victim's browser. Version 4.11.7 patches the issue.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-24771?
CVE-2026-24771 is a Cross-Site Scripting (XSS) vulnerability that can lead to unauthorized script execution in affected applications.
How do I fix CVE-2026-24771?
To fix CVE-2026-24771, upgrade the hono/jsx library to version 4.11.7 or later.
Which versions are affected by CVE-2026-24771?
CVE-2026-24771 affects versions of the hono/jsx library prior to 4.11.7.
What are the implications of CVE-2026-24771?
The implications of CVE-2026-24771 include the potential for attackers to execute arbitrary scripts in the context of a user's session.
Is CVE-2026-24771 exploitable in all use cases of hono?
CVE-2026-24771 is conditionally exploitable based on certain usage patterns in the ErrorBoundary component.