CVE-2020-27771 Explained : Impact and Mitigation

CVE-2020-27771 is a vulnerability in ImageMagick that could lead to application availability issues when processing crafted PDF files. This article provides insights into the nature of the vulnerability, its impact, technical details, and mitigation strategies.

Understanding CVE-2020-27771

What is CVE-2020-27771?

In the RestoreMSCWarning() function of /coders/pdf.c in ImageMagick versions prior to 7.0.9-0, there are potential unsigned char type overflow issues due to improper handling of return values from GetPixelIndex().

The Impact of CVE-2020-27771

This vulnerability could result in undefined behavior when processing malicious PDF files, potentially affecting application availability. Red Hat Product Security rates this as Low severity due to the lack of demonstrated specific impacts in this instance.

Technical Details of CVE-2020-27771

Vulnerability Description

The vulnerability arises from improper casting of return values from GetPixelIndex() in ImageMagick's code, leading to potential unsigned char type overflow.

Affected Systems and Versions

Vendor: n/a
Product: ImageMagick
Vulnerable Version: ImageMagick 7.0.9-0

Exploitation Mechanism

The vulnerability can be exploited by crafting PDF files to trigger the improper handling of return values, potentially causing application availability issues.

Mitigation and Prevention

Immediate Steps to Take

Update ImageMagick to version 7.0.9-0 or later to mitigate the vulnerability.
Exercise caution when processing PDF files from untrusted sources.

Long-Term Security Practices

Regularly update software and libraries to the latest versions to address known vulnerabilities.
Implement file type and content validation mechanisms to prevent the exploitation of similar vulnerabilities.

Patching and Updates

Apply security patches provided by ImageMagick promptly to address CVE-2020-27771 and other potential vulnerabilities.