CVE-2020-26537
📋 TL;DR
CVE-2020-26537 is a critical memory corruption vulnerability in Foxit Reader and PhantomPDF that allows attackers to execute arbitrary code by exploiting an out-of-bounds write during PDF shading calculations. This affects all users of vulnerable Foxit software versions who open malicious PDF files. Successful exploitation gives attackers the same privileges as the current user.
💻 Affected Systems
- Foxit Reader
- Foxit PhantomPDF
📦 What is this software?
Foxit Reader by Foxitsoftware
Phantompdf by Foxitsoftware
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through remote code execution, allowing attackers to install malware, steal data, or create persistent backdoors.
Likely Case
Malicious PDFs delivered via email or web downloads lead to system compromise, ransomware deployment, or credential theft.
If Mitigated
With proper security controls, exploitation attempts are blocked by endpoint protection, and impact is limited to application crashes.
🎯 Exploit Status
Exploitation requires user interaction to open a malicious PDF file. The vulnerability is in the core PDF rendering 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 version 10.1 or later from official Foxit website. 2. Run the installer. 3. Follow installation prompts. 4. Verify version is 10.1+ in Help > About.
🔧 Temporary Workarounds
Disable JavaScript in Foxit
allDisabling JavaScript reduces attack surface but doesn't fully mitigate this specific vulnerability
File > Preferences > JavaScript > Uncheck 'Enable JavaScript'
Use Protected View
allEnable Protected View to open untrusted PDFs in sandboxed mode
File > Preferences > Trust Manager > Check 'Enable Protected View'
🧯 If You Can't Patch
- Use alternative PDF readers like Adobe Reader or browser-based PDF viewers
- Implement application whitelisting to block Foxit Reader execution
🔍 How to Verify
Check if Vulnerable:
Open Foxit Reader/PhantomPDF, go to Help > About and check if version is below 10.1Check Version:
On Windows: wmic product where name like "Foxit%" get versionVerify Fix Applied:
Confirm version is 10.1 or higher in Help > About dialog📡 Detection & Monitoring
Log Indicators:
- Application crashes in Foxit Reader/PhantomPDF
- 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 parent_process_name:"FoxitReader.exe")