CVE-2025-68616
📋 TL;DR
WeasyPrint versions before 68.0 contain an SSRF protection bypass vulnerability in the default_url_fetcher. Attackers can exploit HTTP redirects to access internal network resources like localhost services or cloud metadata endpoints, even when developers have implemented custom security policies. This affects any application using WeasyPrint to generate PDFs from untrusted HTML input.
💻 Affected Systems
- WeasyPrint
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of internal network services, including access to cloud metadata endpoints (potentially exposing credentials), internal APIs, and sensitive localhost services.
Likely Case
Information disclosure from internal services, enumeration of internal network resources, and potential access to cloud metadata containing temporary credentials.
If Mitigated
Limited impact if proper network segmentation and egress filtering are in place, though some internal resource enumeration may still occur.
🎯 Exploit Status
Exploitation requires the ability to control HTML content being converted to PDF. The vulnerability is straightforward to exploit once an attacker controls input.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 68.0
Vendor Advisory: https://github.com/Kozea/WeasyPrint/security/advisories/GHSA-983w-rhvv-gwmv
Restart Required: No
Instructions:
1. Update WeasyPrint to version 68.0 or later using pip: pip install --upgrade weasyprint==68.0
2. Verify the update completed successfully
3. Test PDF generation functionality to ensure compatibility
🔧 Temporary Workarounds
Implement custom URL fetcher with redirect validation
allCreate a custom url_fetcher that validates redirect destinations against security policies
Implement custom fetcher that checks response.url after redirects
Network egress filtering
allBlock outbound connections from WeasyPrint servers to internal network ranges
Configure firewall rules to restrict WeasyPrint server egress traffic
🧯 If You Can't Patch
- Implement strict input validation and sanitization for HTML content processed by WeasyPrint
- Deploy network segmentation to isolate WeasyPrint servers from sensitive internal resources
🔍 How to Verify
Check if Vulnerable:
Check WeasyPrint version: python -c "import weasyprint; print(weasyprint.__version__)" and verify it's below 68.0Check Version:
python -c "import weasyprint; print(weasyprint.__version__)"Verify Fix Applied:
After updating, test with a controlled SSRF attempt using redirects to internal resources📡 Detection & Monitoring
Log Indicators:
- Unusual outbound connections from WeasyPrint processes to internal IP ranges
- Multiple redirects in URL fetching operations
Network Indicators:
- HTTP traffic from WeasyPrint servers to internal/private IP addresses
- Requests to cloud metadata endpoints from application servers
SIEM Query:
source="weasyprint" AND (dest_ip=10.0.0.0/8 OR dest_ip=172.16.0.0/12 OR dest_ip=192.168.0.0/16 OR dest_ip=169.254.169.254)