CVE-2021-40731 Explained : Impact and Mitigation

Adobe Acrobat Reader DC version 21.007.20095 and earlier, 21.007.20096 and earlier, 20.004.30015 and earlier, and 17.011.30202 and earlier are affected by an out-of-bounds write vulnerability when parsing a crafted JPEG2000 file. This could lead to arbitrary code execution with high impact.

Understanding CVE-2021-40731

Adobe Acrobat Reader DC is susceptible to a remote code execution vulnerability due to mishandling of JPEG2000 files.

What is CVE-2021-40731?

The CVE-2021-40731 vulnerability involves an out-of-bounds write flaw that arises when Adobe Acrobat Reader DC processes a specially crafted JPEG2000 file. Attackers can exploit this to execute arbitrary code within the user's context.

The Impact of CVE-2021-40731

The vulnerability has a CVSS v3.0 Base Score of 7.8, indicating a high severity issue. The key impacts are as follows:

Attack Complexity: Low
Attack Vector: Local
Confidentiality Impact: High
Integrity Impact: High
Availability Impact: High
User Interaction: Required

Technical Details of CVE-2021-40731

Adobe Acrobat Reader DC's vulnerability is detailed as follows:

Vulnerability Description

The vulnerability is categorized under CWE-787 (Out-of-bounds Write) and allows an out-of-bounds write attack during the processing of a malicious JPEG2000 file.

Affected Systems and Versions

Product: Acrobat Reader
Vendor: Adobe
Affected Versions:
<= 21.007.20095
<= 21.007.20096
<= 20.004.30015
<= 17.011.30202

Exploitation Mechanism

Exploiting this vulnerability requires a victim to open a malicious file crafted in a specific manner. A successful exploit grants attackers the ability to execute arbitrary code in the victim's context.

Mitigation and Prevention

To address CVE-2021-40731, follow these steps:

Immediate Steps to Take

Update Adobe Acrobat Reader to the latest version.
Avoid opening files from untrusted sources.
Exercise caution while interacting with attachments.

Long-Term Security Practices

Regularly update software and security patches.
Implement security awareness training to recognize phishing attempts.
Consider using alternative PDF readers as a supplementary security measure.

Patching and Updates

Adobe has released a security advisory with patches to address the vulnerability. It is crucial to promptly apply these updates to protect systems from potential exploitation.