CVE-2021-34973
📋 TL;DR
CVE-2021-34973 is a use-after-free vulnerability in Foxit PDF Reader's PDF file parsing that allows attackers to disclose sensitive information. Users who open malicious PDF files or visit malicious web pages are affected. This vulnerability can be combined with other exploits to potentially execute arbitrary code.
💻 Affected Systems
- Foxit PDF Reader
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers combine this information disclosure vulnerability with other exploits to achieve remote code execution, potentially compromising the entire system.
Likely Case
Sensitive information from memory is disclosed, which could include credentials, session data, or other confidential information.
If Mitigated
With proper controls, only limited information disclosure occurs without code execution.
🎯 Exploit Status
Requires user interaction and combination with other vulnerabilities for full exploitation
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 11.1.0.52543 and later
Vendor Advisory: https://www.foxit.com/support/security-bulletins.html
Restart Required: Yes
Instructions:
1. Download latest version from Foxit website 2. Run installer 3. Restart system 4. Verify version is 11.1.0.52543 or higher
🔧 Temporary Workarounds
Disable JavaScript in PDF Reader
windowsPrevents malicious JavaScript execution in PDF files
Open Foxit Reader > File > Preferences > JavaScript > Uncheck 'Enable JavaScript'
Use Protected View
windowsOpen PDFs in sandboxed protected view mode
Open Foxit Reader > File > Preferences > General > Check 'Open documents in Protected View'
🧯 If You Can't Patch
- Block PDF files from untrusted sources at network perimeter
- Use alternative PDF reader software temporarily
🔍 How to Verify
Check if Vulnerable:
Check Foxit Reader version in Help > AboutCheck Version:
wmic product where name="Foxit Reader" get versionVerify Fix Applied:
Verify version is 11.1.0.52543 or higher in Help > About📡 Detection & Monitoring
Log Indicators:
- Multiple PDF parsing errors in application logs
- Unexpected memory access patterns
Network Indicators:
- Downloads of PDF files from suspicious sources
- Outbound connections after PDF opening
SIEM Query:
source="foxit_reader.log" AND (event="memory_access_violation" OR event="pdf_parse_error")