CVE-2021-39836 Explained : Impact and Mitigation

Adobe Acrobat Reader DC versions 2021.005.20060 and earlier, 2020.004.30006 and earlier, and 2017.011.30199 and earlier are affected by a use-after-free vulnerability in the AcroForm buttonGetIcon processing, enabling remote code execution with user interaction.

Understanding CVE-2021-39836

A critical vulnerability affecting Adobe Acrobat Reader DC with the potential for arbitrary code execution.

What is CVE-2021-39836?

Use-after-free vulnerability in Acrobat Reader DC versions prior to 2021.005.20060, 2020.004.30006, and 2017.011.30199
Exploitation requires user interaction through opening a malicious file

The Impact of CVE-2021-39836

CVSS Score: 7.8 (High)
Attack Vector: Local
User Interaction: Required
Affected Confidentiality, Integrity, and Availability: High

Technical Details of CVE-2021-39836

A deep dive into the technical aspects of the vulnerability.

Vulnerability Description

Type: Use After Free (CWE-416)
Description: Vulnerability in AcroForm buttonGetIcon action processing

Affected Systems and Versions

Acrobat Reader DC versions 2021.005.20060 and earlier
Acrobat Reader DC versions 2020.004.30006 and earlier
Acrobat Reader DC versions 2017.011.30199 and earlier
Custom versions based on DC 2021 July and earlier

Exploitation Mechanism

Vulnerability exploited through the processing of the AcroForm buttonGetIcon action
Resulting in arbitrary code execution in the context of the current user

Mitigation and Prevention

Steps to protect systems from CVE-2021-39836.

Immediate Steps to Take

Update Acrobat Reader to a non-vulnerable version
Exercise caution when opening PDF files from untrusted sources

Long-Term Security Practices

Regularly update software to the latest versions
Implement security awareness training for users

Patching and Updates

Adobe has released security updates to address the vulnerability