CVE-2021-20247 : Vulnerability Insights and Analysis

A flaw was discovered in mbsync versions before 1.3.5 and 1.4.1, where the mailbox name validations were insufficient, allowing a malicious or compromised server to access data outside the designated mailbox through specially crafted mailbox names. This vulnerability poses a serious risk to data confidentiality and integrity.

Understanding CVE-2021-20247

This section will discuss the impact of the CVE-2021-20247 vulnerability and provide technical details regarding affected systems, exploitation mechanisms, and mitigation strategies.

What is CVE-2021-20247?

The vulnerability in mbsync versions before 1.3.5 and 1.4.1 allows a malicious server to manipulate mailbox names and access data beyond the intended scope, compromising data confidentiality and integrity.

The Impact of CVE-2021-20247

The main threat from this vulnerability is the unauthorized access to sensitive data stored in mailboxes due to inadequate validations, leading to potential data breaches and integrity issues.

Technical Details of CVE-2021-20247

This section provides insights into the vulnerability description, affected systems, versions, and the mechanism through which the exploitation can occur.

Vulnerability Description

The flaw in mbsync versions before 1.3.5 and 1.4.1 allows servers to use crafted mailbox names with '..' path components to traverse beyond the designated mailbox, potentially accessing and compromising sensitive data.

Affected Systems and Versions

The vulnerability impacts mbsync versions before 1.3.5 and 1.4.1, allowing attackers to exploit the flaw in systems using these versions, compromising data confidentiality.

Exploitation Mechanism

By manipulating mailbox names returned by IMAP LIST/LSUB commands, a malicious or compromised server can trick mbsync into accessing unauthorized data outside the intended mailbox, violating data integrity and confidentiality.

Mitigation and Prevention

This section outlines immediate steps to take, long-term security practices, and the importance of applying patches and updates to address CVE-2021-20247.

Immediate Steps to Take

Users are advised to update mbsync to versions 1.3.5 and 1.4.1 or later to mitigate the vulnerability. It is crucial to monitor for any suspicious activities in mailbox synchronization processes.

Long-Term Security Practices

To enhance security, organizations should implement strict input validations, conduct regular security audits, and educate users about safe practices in email communication and data handling.

Patching and Updates

Regularly check for security advisories from the vendor and apply patches promptly. Keeping software updated to the latest versions is essential in preventing exploitation of known vulnerabilities.