CVE-2026-22817
📋 TL;DR
This vulnerability in Hono's JWT middleware allows attackers to forge authentication tokens through algorithm confusion. Applications using Hono's JWT verification with JWK/JWKS without explicitly specifying the algorithm are affected, potentially leading to 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.
Likely Case
Authentication bypass enabling unauthorized access to protected resources or user impersonation.
If Mitigated
Limited impact with proper JWT configuration and algorithm specification.
🎯 Exploit Status
JWT algorithm confusion attacks are well-documented and relatively easy to execute with available tooling.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.11.4
Vendor Advisory: https://github.com/honojs/hono/security/advisories/GHSA-f67f-6cw9-8mq4
Restart Required: Yes
Instructions:
1. Update Hono package to version 4.11.4 or later. 2. Ensure JWT middleware explicitly specifies the alg option. 3. Restart the application.
🔧 Temporary Workarounds
Explicit Algorithm Specification
allManually specify the algorithm in JWT middleware configuration to prevent header-based algorithm selection
// In Hono JWT middleware configuration, add: alg: 'RS256' (or your specific algorithm)
🧯 If You Can't Patch
- Implement additional JWT validation layer outside Hono middleware
- Use API gateway or WAF to validate JWT tokens before they reach the application
🔍 How to Verify
Check if Vulnerable:
Check package.json for Hono version <4.11.4 and review JWT middleware configuration for missing alg parameterCheck Version:
npm list honoVerify Fix Applied:
Verify Hono version is 4.11.4+ and JWT middleware includes explicit alg parameter📡 Detection & Monitoring
Log Indicators:
- Failed JWT validations with algorithm mismatch errors
- Unusual authentication patterns
Network Indicators:
- JWT tokens with modified alg headers
- Authentication attempts with malformed tokens
SIEM Query:
source="application_logs" AND ("JWT validation failed" OR "algorithm mismatch")