CVE-2021-40420 : What You Need to Know

This article provides detailed information about CVE-2021-40420, a use-after-free vulnerability in Foxit Reader 11.1.0.52543.

Understanding CVE-2021-40420

CVE-2021-40420 is a high-severity vulnerability in Foxit Reader 11.1.0.52543 that could allow an attacker to execute arbitrary code.

What is CVE-2021-40420?

A use-after-free vulnerability exists in the JavaScript engine of Foxit Software’s PDF Reader, version 11.1.0.52543. This flaw can be triggered by a specially-crafted PDF document, leading to arbitrary code execution if exploited.

The Impact of CVE-2021-40420

CVSS Base Score: 8.8 (High)
Attack Vector: Network
Confidentiality Impact: High
Integrity Impact: High
Availability Impact: High
User Interaction: Required
Privileges Required: None
Exploitation: Requires user interaction to open a malicious file or visit a specially-crafted site with certain browser settings.

Technical Details of CVE-2021-40420

This section delves into the technical aspects of the vulnerability.

Vulnerability Description

The vulnerability arises from a use-after-free issue in the JavaScript engine of Foxit Reader 11.1.0.52543, allowing the reuse of previously freed memory upon triggering specific actions.

Affected Systems and Versions

Product: Foxit Reader
Version: 11.1.0.52543

Exploitation Mechanism

Triggered by opening a specially-crafted malicious PDF file
Potential exploitation via visiting a malicious site with enabled browser plugin extension

Mitigation and Prevention

Understanding how to mitigate and prevent the CVE-2021-40420 vulnerability is crucial.

Immediate Steps to Take

Update Foxit Reader to the latest version
Be cautious while opening PDF files from untrusted sources
Disable browser plugins/extensions if not necessary

Long-Term Security Practices

Regularly update software and security patches
Educate users on safe browsing habits and file handling

Patching and Updates

Apply vendor-supplied patches promptly