CVE-2026-22818
📋 TL;DR
This vulnerability in Hono's JWT verification middleware allows algorithm confusion attacks, enabling attackers to forge JWT tokens that could be accepted as valid. It affects Hono applications using JWK/JWKS JWT verification middleware prior to version 4.11.4. Attackers could potentially bypass authentication or gain unauthorized access.
💻 Affected Systems
- Hono
📦 What is this software?
Hono by Hono
⚠️ Risk & Real-World Impact
Worst Case
Complete authentication bypass allowing attackers to impersonate any user, access sensitive data, or perform privileged actions within the application.
Likely Case
Authentication bypass for some users, potentially allowing unauthorized access to protected resources or functionality.
If Mitigated
No impact if proper algorithm allowlisting is already implemented or if the application doesn't use JWT authentication.
🎯 Exploit Status
Algorithm confusion attacks are well-documented and relatively easy to execute with available JWT manipulation tools.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.11.4
Vendor Advisory: https://github.com/honojs/hono/security/advisories/GHSA-3vhc-576x-3qv4
Restart Required: Yes
Instructions:
1. Update Hono package to version 4.11.4 or later using npm: npm update hono@^4.11.4
2. Restart your application
3. Verify the update was successful
🔧 Temporary Workarounds
Implement explicit algorithm allowlist
allManually configure JWT verification to only accept specific algorithms rather than deriving from JWT header
// In your Hono JWT middleware configuration:
// Specify allowed algorithms explicitly
const jwtMiddleware = jwt({
secret: jwks,
alg: ['RS256', 'ES256'] // Explicit allowlist of acceptable algorithms
})
🧯 If You Can't Patch
- Implement network-level controls to restrict access to vulnerable applications
- Add additional authentication layers or implement rate limiting on authentication endpoints
🔍 How to Verify
Check if Vulnerable:
Check your package.json or package-lock.json for Hono version. If version is <4.11.4 and you use JWK/JWKS JWT middleware, you are vulnerable.Check Version:
npm list hono | grep honoVerify Fix Applied:
Verify Hono version is 4.11.4 or higher and test JWT authentication with various algorithm headers to ensure only allowed algorithms are accepted.📡 Detection & Monitoring
Log Indicators:
- Multiple failed JWT validations with different algorithm headers
- Successful authentications with unexpected algorithm types
- JWT validation errors mentioning algorithm mismatches
Network Indicators:
- Unusual authentication patterns
- Multiple authentication attempts with varying JWT headers
- Requests with manipulated JWT algorithm claims
SIEM Query:
source="application_logs" AND ("JWT validation failed" OR "algorithm" OR "signature verification") AND NOT "RS256" AND NOT "ES256"