CVE-2021-39849 : Exploit Details and Defense Strategies

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 Null pointer dereference vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve an application denial-of-service in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

Understanding CVE-2021-39849

Adobe Acrobat Reader DC has a vulnerability that could result in denial-of-service when exploited by an attacker.

What is CVE-2021-39849?

The CVE-2021-39849 vulnerability in Adobe Acrobat Reader DC allows unauthenticated attackers to cause denial-of-service, impacting the application functionality for the current user.

The Impact of CVE-2021-39849

The vulnerability has a CVSS base score of 5.5 indicating a medium severity level. It requires low attack complexity, a local attack vector, and user interaction. If exploited, it could lead to a high availability impact.

Technical Details of CVE-2021-39849

Adobe Acrobat Reader DC vulnerability details and impact.

Vulnerability Description

The vulnerability is a Null pointer dereference issue, categorized under CWE-476. An attacker could exploit this to trigger a denial-of-service attack.

Affected Systems and Versions

Product: Acrobat Reader
Vendor: Adobe
Versions affected: DC 2021 July, 20.0-Classic 2021 July, 17.0-Classic 2021 July, None

Exploitation Mechanism

To exploit the vulnerability, an unauthenticated attacker needs to persuade the victim to open a specifically crafted malicious file, leading to application denial-of-service.

Mitigation and Prevention

Mitigation strategies to address the CVE-2021-39849 vulnerability.

Immediate Steps to Take

Update Adobe Acrobat Reader DC to the patched versions or latest release.
Be cautious while opening files from untrusted or unknown sources.
Employ security software to detect and block potentially malicious files.

Long-Term Security Practices

Regularly update software to ensure the latest security patches are applied.
Educate users on safe browsing practices and avoiding suspicious file downloads.

Patching and Updates

Regularly check for updates from Adobe and apply patches promptly to protect systems from known vulnerabilities.