CVE-2020-23876
📋 TL;DR
CVE-2020-23876 is a memory leak vulnerability in pdf2xml v2.0's TextPage::testLinkedText function that allows attackers to cause denial of service through resource exhaustion. This affects systems running pdf2xml v2.0 to process PDF files. Organizations using pdf2xml for PDF conversion are at risk.
💻 Affected Systems
- pdf2xml
📦 What is this software?
Pdf2xml by Science Miner
⚠️ Risk & Real-World Impact
Worst Case
Complete system crash or service disruption due to memory exhaustion, potentially affecting availability of systems using pdf2xml for PDF processing.
Likely Case
Degraded performance and eventual service termination of pdf2xml processes when processing malicious PDF files, requiring manual intervention to restart services.
If Mitigated
Minimal impact with proper memory limits and monitoring in place, allowing for graceful degradation rather than complete failure.
🎯 Exploit Status
Exploitation requires feeding malicious PDF files to pdf2xml; proof-of-concept code is publicly available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version after 2.0 (check latest release)
Vendor Advisory: https://github.com/kermitt2/pdf2xml/issues/14
Restart Required: Yes
Instructions:
1. Check current pdf2xml version. 2. Update to latest version from official repository. 3. Restart any services using pdf2xml. 4. Test with known PDF files to ensure functionality.
🔧 Temporary Workarounds
Memory Limit Enforcement
linuxSet memory limits on pdf2xml processes to prevent complete system exhaustion
ulimit -v 1048576
systemctl set-property pdf2xml.service MemoryLimit=1G
Input Validation
allImplement PDF file validation before processing with pdf2xml
🧯 If You Can't Patch
- Isolate pdf2xml to dedicated systems with limited resources
- Implement strict monitoring and alerting for memory usage spikes
🔍 How to Verify
Check if Vulnerable:
Check pdf2xml version: 'pdf2xml --version' or examine installed package versionCheck Version:
pdf2xml --versionVerify Fix Applied:
Test with proof-of-concept PDF from references; monitor memory usage during processing📡 Detection & Monitoring
Log Indicators:
- Abnormal memory consumption patterns
- Process crashes or restarts
- High swap usage
Network Indicators:
- Unusual PDF file uploads to systems using pdf2xml
SIEM Query:
Process:name="pdf2xml" AND (MemoryUsage>90% OR ProcessTerminated)