CVE-2026-24771
📋 TL;DR
This Cross-Site Scripting (XSS) vulnerability in Hono's ErrorBoundary component allows attackers to inject malicious scripts that execute in victims' browsers when viewing pages with untrusted user input. Applications using Hono's JSX library versions before 4.11.7 are affected. The vulnerability requires specific usage patterns where user-controlled strings are rendered as raw HTML.
💻 Affected Systems
- Hono JSX library
📦 What is this software?
Hono by Hono
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal session cookies, perform actions as authenticated users, deface websites, or redirect users to malicious sites, potentially leading to account compromise and data theft.
Likely Case
Attackers inject malicious scripts to steal session tokens or user data from vulnerable pages, potentially compromising user accounts on the affected application.
If Mitigated
With proper Content Security Policy (CSP) headers and input validation, impact is limited to script execution within CSP constraints, though data exfiltration may still occur.
🎯 Exploit Status
Exploitation requires finding vulnerable ErrorBoundary usage patterns and injecting malicious payloads. No public exploit code has been identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.11.7
Vendor Advisory: https://github.com/honojs/hono/security/advisories/GHSA-9r54-q6cx-xmh5
Restart Required: Yes
Instructions:
1. Update Hono package to version 4.11.7 or later using npm/yarn/pnpm. 2. Restart your application server. 3. Verify the update was successful by checking package.json and running the application.
🔧 Temporary Workarounds
Implement Content Security Policy
allAdd strict CSP headers to prevent script execution from untrusted sources
Sanitize ErrorBoundary Input
allManually sanitize any user input passed to ErrorBoundary components before rendering
🧯 If You Can't Patch
- Implement strict Content Security Policy headers with script-src directives
- Review and sanitize all user input passed to ErrorBoundary components
🔍 How to Verify
Check if Vulnerable:
Check package.json for Hono version below 4.11.7 and review ErrorBoundary component usage for unsanitized user input rendering.Check Version:
npm list hono | grep hono OR check package.json for "hono" versionVerify Fix Applied:
Verify package.json shows Hono version 4.11.7 or higher and test ErrorBoundary functionality with test payloads.📡 Detection & Monitoring
Log Indicators:
- Unusual error messages containing script tags or JavaScript code in ErrorBoundary contexts
- Multiple failed requests to error handling endpoints
Network Indicators:
- HTTP requests containing script payloads in error-related parameters
- Unexpected outbound connections from client browsers after error pages
SIEM Query:
source="application_logs" AND ("ErrorBoundary" OR "error") AND ("<script>" OR "javascript:" OR "onerror=")