CVE-2025-63721
📋 TL;DR
This vulnerability in HummerRisk allows authenticated users with normal privileges to exploit a vulnerable Snakeyaml component via the /rule/add API endpoint, leading to remote code execution and potential server takeover. All HummerRisk deployments through version 1.5.0 are affected.
💻 Affected Systems
- HummerRisk
📦 What is this software?
Hummerrisk by Hummerrisk
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise with attacker gaining full control over the system, data exfiltration, lateral movement, and persistent backdoor installation.
Likely Case
Attacker executes arbitrary code with the privileges of the HummerRisk service account, potentially accessing sensitive data and establishing persistence.
If Mitigated
With proper network segmentation and least privilege, impact limited to the HummerRisk application container/service.
🎯 Exploit Status
Exploitation requires authenticated user access but is straightforward once authenticated. Public proof-of-concept demonstrates the attack chain.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Monitor HummerRisk GitHub repository for security updates. 2. When patch is released, update to the fixed version. 3. Restart HummerRisk services after update.
🔧 Temporary Workarounds
Disable /rule/add endpoint
allBlock access to the vulnerable API endpoint via web application firewall or reverse proxy configuration.
# Example nginx location block
location /rule/add { deny all; }
# Example Apache .htaccess
<Location "/rule/add">
Order deny,allow
Deny from all
</Location>
Restrict user privileges
allTemporarily remove rule management permissions from normal users until patch is available.
# Review and modify user roles in HummerRisk admin panel
# Remove 'rule management' or similar permissions from standard user roles
🧯 If You Can't Patch
- Network segmentation: Isolate HummerRisk servers from critical systems and restrict inbound/outbound connections.
- Enhanced monitoring: Implement strict logging and alerting for suspicious API calls to /rule/add endpoint.
🔍 How to Verify
Check if Vulnerable:
Check HummerRisk version via web interface admin panel or by examining deployment configuration files. If version is 1.5.0 or earlier, system is vulnerable.Check Version:
# Check Docker container version
docker ps | grep hummerrisk
# Or check application logs for version informationVerify Fix Applied:
After applying workarounds, test that authenticated users cannot access /rule/add endpoint or that the endpoint returns appropriate access denied responses.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /rule/add endpoint
- YAML parsing errors or unusual payloads in rule management
- Suspicious process execution from HummerRisk service account
Network Indicators:
- Unusual outbound connections from HummerRisk server
- Traffic patterns indicating data exfiltration
SIEM Query:
source="hummerrisk" AND (url_path="/rule/add" OR message="*Snakeyaml*" OR message="*YAML*" AND severity=ERROR)