CVE-2021-3403 : Security Advisory and Response

In ytnef 1.9.3, the TNEFSubjectHandler function in lib/ytnef.c allows remote attackers to cause a denial-of-service (and potentially code execution) due to a double free which can be triggered via a crafted file.

Understanding CVE-2021-3403

This CVE identifies a vulnerability in ytnef 1.9.3 that can enable remote attackers to execute a denial-of-service attack with potential for code execution.

What is CVE-2021-3403?

CVE-2021-3403 is a security flaw in the TNEFSubjectHandler function of ytnef 1.9.3 that permits malicious actors to instigate a denial-of-service event and potentially execute arbitrary code by exploiting a double free occurrence through a specially crafted file.

The Impact of CVE-2021-3403

The impact of CVE-2021-3403 could lead to service disruptions and, in severe cases, unauthorized remote code execution, posing a significant threat to the integrity and availability of affected systems.

Technical Details of CVE-2021-3403

This section delves into the technical aspects of the CVE, including its vulnerability description, affected systems and versions, and exploitation mechanism.

Vulnerability Description

The vulnerability lies in the TNEFSubjectHandler function in ytnef 1.9.3, allowing remote attackers to invoke a double free scenario by manipulating specific file inputs, consequently leading to denial-of-service and potential code execution.

Affected Systems and Versions

All versions of ytnef are impacted by CVE-2021-3403, making a wide range of systems vulnerable to exploitation if left unmitigated.

Exploitation Mechanism

Remote attackers can exploit this vulnerability by creating a malicious file that triggers the double free issue in the TNEFSubjectHandler function, opening avenues for carrying out denial-of-service attacks and unauthorized code execution.

Mitigation and Prevention

Here, we outline immediate steps to take and long-term security practices to safeguard systems against CVE-2021-3403.

Immediate Steps to Take

To mitigate the risk associated with CVE-2021-3403, users are advised to promptly update ytnef to a non-vulnerable version and exercise caution while handling untrusted file attachments.

Long-Term Security Practices

Implementing a robust security posture that includes regular software patching, security training for users, and monitoring for suspicious file activities can fortify defenses against similar vulnerabilities in the future.

Patching and Updates

Stay informed about security advisories and updates from the software vendor to deploy patches promptly and ensure that systems are protected against known vulnerabilities.