CVE-2021-39839 : Exploit Details and Defense Strategies

Adobe Acrobat Reader DC versions are affected by a use-after-free vulnerability that could lead to remote code execution.

Understanding CVE-2021-39839

Adobe Acrobat Reader DC has a vulnerability that attackers could exploit for remote code execution.

What is CVE-2021-39839?

Acrobat Reader DC versions impacted: 2021.005.20060 and earlier, 2020.004.30006 and earlier, 2017.011.30199 and earlier.
Vulnerability: Use-after-free issue in processing AcroForm getItem action.
Risk: Allows attackers to execute arbitrary code in the user's context.

The Impact of CVE-2021-39839

CVSS Score: 7.8 (High Severity).
Attack Vector: Local.
User Interaction: Required.
Confidentiality, Integrity, and Availability Impact: High.
Scope: Unchanged.
Exploitation: Requires victim to open a malicious file.

Technical Details of CVE-2021-39839

The technical details of the vulnerability and its implications.

Vulnerability Description

The vulnerability lies in the AcroForm getItem action processing, leading to a use-after-free vulnerability.

Affected Systems and Versions

Products: Acrobat Reader by Adobe.
Versions: DC 2021 July, 20.0-Classic 2021 July, 17.0-Classic 2021 July, and earlier.

Exploitation Mechanism

To exploit, the attacker must entice a victim to open a malicious file, triggering arbitrary code execution.

Mitigation and Prevention

Measures to mitigate and prevent exploitation of CVE-2021-39839.

Immediate Steps to Take

Update Acrobat Reader to the latest patched versions.
Exercise caution when opening files from untrusted sources.

Long-Term Security Practices

Regularly update software and security patches.
Implement robust cybersecurity awareness training.

Patching and Updates

Adobe has released security updates to address the vulnerability.