CVE-2025-2997
📋 TL;DR
This critical vulnerability in Youkefu 4.2.0 allows remote attackers to perform server-side request forgery (SSRF) attacks by manipulating the 'url' parameter in the /res/url endpoint. Attackers can exploit this to make the server send unauthorized requests to internal systems. All users running Youkefu 4.2.0 are affected.
💻 Affected Systems
- zhangyanbo2007 youkefu
📦 What is this software?
Youkefu by Zhangyanbo2007
⚠️ Risk & Real-World Impact
Worst Case
Attackers could pivot to internal systems, access sensitive data, perform internal reconnaissance, or execute commands on internal services via SSRF.
Likely Case
Unauthorized access to internal HTTP services, data exfiltration from internal systems, or scanning of internal network segments.
If Mitigated
Limited to external resource access if proper network segmentation and egress filtering are implemented.
🎯 Exploit Status
Exploit details are publicly available in GitHub repositories, making this easily exploitable.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: No
Instructions:
No official patch available. Check the Youkefu GitHub repository or vendor channels for updates.
🔧 Temporary Workarounds
Block /res/url endpoint
allUse web application firewall or reverse proxy to block access to the vulnerable endpoint
# Example nginx location block
location /res/url { deny all; }
# Example Apache .htaccess
RedirectMatch 403 ^/res/url
Input validation for URL parameter
allImplement strict validation to only allow trusted URLs or domains
# Application-level validation needed
# Validate URL parameter against whitelist of allowed domains
🧯 If You Can't Patch
- Implement strict network segmentation to limit the server's ability to reach internal systems
- Deploy egress filtering to restrict outbound connections from the Youkefu server
🔍 How to Verify
Check if Vulnerable:
Test if /res/url endpoint accepts arbitrary URLs and makes external requests. Use curl: curl -X POST 'http://youkefu-server/res/url' -d 'url=http://attacker-controlled-site'Check Version:
Check Youkefu version in application interface or configuration filesVerify Fix Applied:
Verify the endpoint no longer accepts arbitrary URLs or that requests are properly validated📡 Detection & Monitoring
Log Indicators:
- Unusual outbound HTTP requests from Youkefu server
- Requests to /res/url with external URLs
- Multiple failed outbound connection attempts
Network Indicators:
- Outbound HTTP requests from Youkefu server to unusual external domains
- Internal systems receiving unexpected requests from Youkefu server
SIEM Query:
source="youkefu-logs" AND (uri="/res/url" OR url_parameter="http")