CVE-2023-39438
📋 TL;DR
CVE-2023-39438 is an authorization bypass vulnerability in CLA-assistant that allows any authenticated user to read, update, or delete CLA (Contributor License Agreement) configurations and signed CLA data. This affects organizations using CLA-assistant to manage contributor agreements, potentially exposing sensitive signer information and allowing unauthorized configuration changes.
💻 Affected Systems
- CLA-assistant
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
An attacker could delete all CLA configurations, disrupt contributor workflows, and access sensitive personal information of all signers including custom fields configured by CLA requesters.
Likely Case
Unauthorized users accessing CLA information and modifying configurations for repositories they shouldn't have access to, potentially disrupting contributor onboarding processes.
If Mitigated
With proper authentication and authorization controls, only authorized administrators can manage CLA configurations and access sensitive signer data.
🎯 Exploit Status
Exploitation requires authentication but no special privileges. The advisory describes specific API endpoints and steps to exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.0.0
Vendor Advisory: https://github.com/cla-assistant/cla-assistant/security/advisories/GHSA-gw8p-frwv-25gh
Restart Required: Yes
Instructions:
1. Update CLA-assistant to version 3.0.0 or later. 2. Restart the CLA-assistant service. 3. Verify that authorization checks are properly implemented for all API endpoints.
🔧 Temporary Workarounds
Restrict API Access
allImplement network-level restrictions to limit access to CLA-assistant API endpoints to only authorized users or systems.
Enhanced Authentication
allImplement additional authentication layers or require multi-factor authentication for accessing CLA-assistant.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate CLA-assistant from untrusted networks
- Monitor API access logs for unauthorized access patterns and implement alerting
🔍 How to Verify
Check if Vulnerable:
Check if CLA-assistant version is below 3.0.0. Review API authorization logic for missing checks on CLA management endpoints.Check Version:
Check the CLA-assistant version in the application interface or deployment configuration.Verify Fix Applied:
After updating to 3.0.0+, test that authenticated users without proper permissions cannot access or modify CLA configurations they shouldn't have access to.📡 Detection & Monitoring
Log Indicators:
- Unauthorized API calls to CLA management endpoints
- Multiple failed authorization attempts followed by successful CLA operations
- Unusual patterns of CLA configuration modifications
Network Indicators:
- Unusual API request patterns to /api/cla/* endpoints from unauthorized users
- Burst of GET/PUT/DELETE requests to CLA management endpoints
SIEM Query:
source="cla-assistant" AND (uri_path="/api/cla/*") AND (user_role!="admin" OR user_role!="authorized")