CVE-2020-21896 Explained : Impact and Mitigation

A detailed overview of CVE-2020-21896, a Use After Free vulnerability in Artifex Software MuPDF 1.16.0.

Understanding CVE-2020-21896

What is CVE-2020-21896?

CVE-2020-21896 is a Use After Free vulnerability found in the svg_dev_text_span_as_paths_defs function in Artifex Software MuPDF 1.16.0. This vulnerability allows remote attackers to trigger a denial of service by opening a specially crafted PDF file.

The Impact of CVE-2020-21896

This vulnerability can be exploited by remote attackers to cause a denial of service on systems running the affected version of MuPDF.

Technical Details of CVE-2020-21896

Vulnerability Description

The vulnerability exists in the svg_dev_text_span_as_paths_defs function in source/fitz/svg-device.c in Artifex Software MuPDF 1.16.0.

Affected Systems and Versions

Vendor: n/a
Product: n/a
Vulnerable Version: 1.16.0

Exploitation Mechanism

Attackers can exploit this vulnerability by tricking a user into opening a malicious PDF file, leading to a Use After Free condition and subsequent denial of service.

Mitigation and Prevention

Immediate Steps to Take

Avoid opening PDF files from untrusted or unknown sources.
Implement network-level protections to filter out potentially malicious PDF files.

Long-Term Security Practices

Keep software and applications up to date to prevent known vulnerabilities.
Conduct regular security audits and penetration testing to identify and address potential weaknesses.

Patching and Updates

Check for patches or updates from Artifex Software to address the CVE-2020-21896 vulnerability.