CVE-2018-20313 – This vulnerability in Foxit Reader and PhantomP... (How to Fix)

Q: What is the severity of CVE-2018-20313?

CVE-2018-20313 has a CVSS score of 8.1 (HIGH). This vulnerability in Foxit Reader and PhantomPDF involves a race condition in the proxyPreviewAction function that can lead to stack-based buffer overflow or out-of-bounds read. Attackers could exploit this to execute arbitrary code or cause denial of service. Users of affected Foxit software versions are at risk.

📋 TL;DR

This vulnerability in Foxit Reader and PhantomPDF involves a race condition in the proxyPreviewAction function that can lead to stack-based buffer overflow or out-of-bounds read. Attackers could exploit this to execute arbitrary code or cause denial of service. Users of affected Foxit software versions are at risk.

💻 Affected Systems

Products:

Foxit Reader
Foxit PhantomPDF

Versions: Foxit Reader before 9.5; PhantomPDF before 8.3.10 and 9.x before 9.5

Operating Systems: Windows, Linux, macOS

Default Config Vulnerable: ⚠️ Yes

Notes: All default installations of affected versions are vulnerable. No special configuration required.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete system compromise, data theft, or ransomware deployment.

🟠

Likely Case

Application crash (denial of service) or limited information disclosure through memory reads.

🟢

If Mitigated

Application crash with no further impact if memory protections are enabled.

🌐 Internet-Facing: MEDIUM - Requires user interaction (opening malicious PDF) but common in document workflows.

🏢 Internal Only: MEDIUM - Same exploitation requirements but internal users may have elevated privileges.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires user to open a malicious PDF file. Race condition exploitation adds complexity but public PoCs exist.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Foxit Reader 9.5+, PhantomPDF 8.3.10+ or 9.5+

Vendor Advisory: https://www.foxitsoftware.com/support/security-bulletins.php

Restart Required: Yes

Instructions:

1. Download latest version from Foxit website. 2. Run installer. 3. Restart system. 4. Verify version is 9.5 or higher.

🔧 Temporary Workarounds

Disable JavaScript in Foxit

all

Prevents JavaScript-based exploitation vectors

Open Foxit > File > Preferences > JavaScript > Uncheck 'Enable JavaScript'

Use Protected View

all

Opens documents in sandboxed mode

Open Foxit > File > Preferences > Trust Manager > Check 'Enable Safe Reading Mode'

🧯 If You Can't Patch

Block PDF files from untrusted sources at network perimeter
Use alternative PDF readers that are not vulnerable

🔍 How to Verify

Check if Vulnerable:

Check Help > About in Foxit software and compare version to affected ranges.

Check Version:

On Windows: wmic product where name like "Foxit%" get version

Verify Fix Applied:

Confirm version is Foxit Reader 9.5+ or PhantomPDF 8.3.10+/9.5+.

📡 Detection & Monitoring

Log Indicators:

Application crashes with Foxit process
Memory access violation errors in system logs

Network Indicators:

PDF downloads from suspicious sources
Unusual outbound connections after PDF opening

SIEM Query:

process_name="FoxitReader.exe" AND (event_id=1000 OR exception_code=0xc0000005)

📊 Metadata

CVE ID: CVE-2018-20313

CVSS v3 Score: 8.1 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-125

Published: January 7, 2021

Last Updated: November 21, 2024

🔗 References

https://www.foxitsoftware.com/support/security-bulletins.php Vendor Advisory
https://www.foxitsoftware.com/support/security-bulletins.php Vendor Advisory

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2018-20313, you might also want to check these: