CVE-2020-26539
📋 TL;DR
This vulnerability in Foxit Reader and PhantomPDF allows attackers to execute arbitrary code on affected systems by exploiting a use-after-free memory error when processing PDF files with malformed /V parameters. All users running vulnerable versions of these applications are at risk of remote code execution or information disclosure.
💻 Affected Systems
- Foxit Reader
- Foxit PhantomPDF
📦 What is this software?
Foxit Reader by Foxitsoftware
Phantompdf by Foxitsoftware
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with remote code execution leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Remote code execution allowing attackers to run malicious code with user privileges, potentially leading to credential theft or lateral movement.
If Mitigated
Application crash or denial of service if memory protections prevent successful exploitation.
🎯 Exploit Status
Exploitation requires user interaction to open a malicious PDF file. The vulnerability is in the core PDF parsing engine.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.1 and later
Vendor Advisory: https://www.foxitsoftware.com/support/security-bulletins.html
Restart Required: No
Instructions:
1. Download Foxit Reader/PhantomPDF 10.1 or later from official website. 2. Run installer. 3. Follow installation prompts. 4. Verify version is 10.1+ in Help > About.
🔧 Temporary Workarounds
Disable JavaScript in Foxit
allPrevents JavaScript-based exploitation vectors
File > Preferences > JavaScript > Uncheck 'Enable JavaScript'
Use Protected View
allOpens PDFs in sandboxed mode to limit damage
File > Preferences > Trust Manager > Check 'Enable Safe Reading Mode'
🧯 If You Can't Patch
- Block PDF files at network perimeter and email gateways
- Use alternative PDF readers that are not vulnerable
🔍 How to Verify
Check if Vulnerable:
Check Help > About in Foxit application. If version is below 10.1, system is vulnerable.Check Version:
On Windows: wmic product where name like "Foxit%" get versionVerify Fix Applied:
Confirm version is 10.1 or higher in Help > About. Test with known malicious PDF samples if available.📡 Detection & Monitoring
Log Indicators:
- Application crashes with memory access violations
- Unexpected child processes spawned from Foxit
Network Indicators:
- Outbound connections from Foxit process to unknown IPs
- DNS requests for suspicious domains after PDF opening
SIEM Query:
process_name:"FoxitReader.exe" AND (event_id:1000 OR event_id:1001) OR process_parent_name:"FoxitReader.exe"