CVE-2023-49208
📋 TL;DR
A buffer overflow vulnerability in Glewlwyd SSO server's FIDO2 credential validation during WebAuthn registration allows attackers to execute arbitrary code or crash the service. This affects all Glewlwyd SSO server instances before version 2.7.6 that have WebAuthn/FIDO2 authentication enabled. Organizations using vulnerable versions for single sign-on are at risk.
💻 Affected Systems
- Glewlwyd SSO Server
📦 What is this software?
Glewlwyd Sso Server by Glewlwyd Sso Server Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, credential theft, or lateral movement within the network.
Likely Case
Service disruption through denial of service, potential authentication bypass, or limited code execution.
If Mitigated
Minimal impact if proper network segmentation and least privilege principles are implemented.
🎯 Exploit Status
Exploitation requires sending specially crafted WebAuthn registration requests to the vulnerable endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.7.6
Vendor Advisory: https://github.com/babelouest/glewlwyd/releases/tag/v2.7.6
Restart Required: Yes
Instructions:
1. Backup current configuration. 2. Download Glewlwyd 2.7.6 from GitHub releases. 3. Stop the Glewlwyd service. 4. Replace with patched version. 5. Restart the service.
🔧 Temporary Workarounds
Disable WebAuthn/FIDO2 Authentication
allTemporarily disable WebAuthn/FIDO2 authentication until patching is possible.
Edit Glewlwyd configuration to remove or comment out WebAuthn/FIDO2 settings
🧯 If You Can't Patch
- Implement network segmentation to isolate Glewlwyd servers from critical systems
- Deploy WAF rules to block suspicious WebAuthn registration attempts
🔍 How to Verify
Check if Vulnerable:
Check if Glewlwyd version is below 2.7.6 and WebAuthn/FIDO2 is enabled in configuration.Check Version:
grep -i version /path/to/glewlwyd/config or check service logsVerify Fix Applied:
Confirm version is 2.7.6 or higher and test WebAuthn registration functionality.📡 Detection & Monitoring
Log Indicators:
- Unusual WebAuthn registration attempts
- Service crashes or restarts
- Buffer overflow error messages
Network Indicators:
- Excessive requests to /api/auth/webauthn/register endpoint
- Malformed WebAuthn registration packets
SIEM Query:
source="glewlwyd.log" AND ("buffer overflow" OR "webauthn registration" AND status=500)