CVE-2021-39857 : Vulnerability Insights and Analysis

Adobe Acrobat Reader DC add-on for Internet Explorer versions is affected by an Information Disclosure vulnerability that could allow an unauthenticated attacker to check for local files' existence.

Understanding CVE-2021-39857

Adobe Acrobat Reader DC Information Disclosure via ActiveX LoadFile

What is CVE-2021-39857?

Adobe Acrobat Reader DC add-on for Internet Explorer versions is vulnerable to an Information Disclosure flaw.
An attacker could exploit this vulnerability to determine the presence of local files.
Exploitation requires user interaction as victims must visit a malicious website.

The Impact of CVE-2021-39857

CVSS Base Score: 4.3 (Medium severity)
Attack Complexity: Low
Attack Vector: Network
User Interaction: Required
Confidentiality Impact: Low

Technical Details of CVE-2021-39857

Adobe Acrobat Reader DC add-on for Internet Explorer versions is affected by an Information Disclosure vulnerability.

Vulnerability Description

Vulnerability Type: Information Exposure (CWE-200)
Affected Versions: DC 2021 July, 20.0-Classic 2021 July, 17.0-Classic 2021 July

Affected Systems and Versions

Adobe Acrobat Reader, versions prior to 2021.005.20060, 2020.004.30006, and 2017.011.30199

Exploitation Mechanism

An unauthenticated attacker could exploit the vulnerability by having a victim visit a malicious website.

Mitigation and Prevention

Adobe recommends the following steps to mitigate the CVE-2021-39857 vulnerability:

Immediate Steps to Take

Upgrade to the latest version of Adobe Acrobat Reader DC.
Avoid visiting untrusted or suspicious websites.
Be cautious when interacting with potentially malicious ActiveX controls or scripts.

Long-Term Security Practices

Regularly update software and security patches.
Implement network perimeter defenses such as firewalls.

Patching and Updates

Adobe has released security updates to address this vulnerability. Ensure you apply the latest patches.