CVE-2021-29451
📋 TL;DR
This vulnerability in Portofino web framework allows attackers to forge valid JSON Web Tokens due to improper signature verification. This affects all Portofino applications using JWT authentication before version 5.2.1, potentially enabling unauthorized access to protected resources.
💻 Affected Systems
- Portofino web framework
📦 What is this software?
Portofino by Manydesigns
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via forged admin tokens leading to data theft, privilege escalation, and remote code execution.
Likely Case
Unauthorized access to protected application functionality, data exposure, and session hijacking.
If Mitigated
Limited impact if additional authentication layers or network segmentation are in place.
🎯 Exploit Status
Exploitation requires ability to generate or modify JWT tokens. No public exploit code available at time of analysis.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.2.1
Vendor Advisory: https://github.com/ManyDesigns/Portofino/security/advisories/GHSA-6g3c-2mh5-7q6x
Restart Required: Yes
Instructions:
1. Update Portofino dependency to version 5.2.1 or later in your project's pom.xml or build.gradle. 2. Rebuild and redeploy your application. 3. Restart application servers.
🔧 Temporary Workarounds
Disable JWT Authentication
allTemporarily disable JWT-based authentication and use alternative authentication methods
Modify application configuration to use session-based or other authentication mechanisms
Implement JWT Validation Proxy
allAdd a reverse proxy or API gateway that validates JWT signatures before requests reach the vulnerable application
Configure nginx, Apache, or API gateway to validate JWT signatures using a secure library
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable applications from sensitive systems
- Add additional authentication layers (multi-factor authentication, IP whitelisting)
🔍 How to Verify
Check if Vulnerable:
Check Portofino version in pom.xml or build.gradle. If version is below 5.2.1 and application uses JWT authentication, it is vulnerable.Check Version:
grep -i portofino pom.xml || grep -i portofino build.gradleVerify Fix Applied:
Verify Portofino version is 5.2.1 or higher in dependencies and test JWT authentication with invalid signatures (should be rejected).📡 Detection & Monitoring
Log Indicators:
- Failed JWT signature validations
- Unexpected successful authentications with malformed tokens
- Authentication attempts with unusual token patterns
Network Indicators:
- HTTP requests with manipulated JWT tokens in Authorization headers
- Unusual authentication patterns from single sources
SIEM Query:
source="application_logs" AND ("JWT validation failed" OR "Invalid signature" OR "Authentication bypass")🔗 References
- https://github.com/ManyDesigns/Portofino/commit/8c754a0ad234555e813dcbf9e57d637f9f23d8fb
- https://github.com/ManyDesigns/Portofino/security/advisories/GHSA-6g3c-2mh5-7q6x
- https://mvnrepository.com/artifact/com.manydesigns/portofino
- https://github.com/ManyDesigns/Portofino/commit/8c754a0ad234555e813dcbf9e57d637f9f23d8fb
- https://github.com/ManyDesigns/Portofino/security/advisories/GHSA-6g3c-2mh5-7q6x
- https://mvnrepository.com/artifact/com.manydesigns/portofino
