CVE-2019-20855 : What You Need to Know

A vulnerability in Mattermost Server versions prior to 5.16.1, 5.15.2, 5.14.5, and 5.9.6 allows malicious actors to access confidential data during legacy attachment migration.

Understanding CVE-2019-20855

This CVE identifies a security issue in Mattermost Server that could lead to unauthorized access to local files.

What is CVE-2019-20855?

The vulnerability in Mattermost Server versions before 5.16.1, 5.15.2, 5.14.5, and 5.9.6 enables attackers to obtain sensitive information stored in local files while performing legacy attachment migration.

The Impact of CVE-2019-20855

The exploitation of this vulnerability could result in unauthorized access to confidential data, potentially leading to data breaches and privacy violations.

Technical Details of CVE-2019-20855

This section provides more technical insights into the vulnerability.

Vulnerability Description

The issue allows attackers to extract sensitive information from local files during the migration of legacy attachments in Mattermost Server.

Affected Systems and Versions

Mattermost Server versions prior to 5.16.1
Mattermost Server versions prior to 5.15.2
Mattermost Server versions prior to 5.14.5
Mattermost Server versions prior to 5.9.6

Exploitation Mechanism

Attackers can exploit this vulnerability by leveraging the legacy attachment migration process to gain unauthorized access to confidential data stored locally.

Mitigation and Prevention

Protecting systems from CVE-2019-20855 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update Mattermost Server to versions 5.16.1, 5.15.2, 5.14.5, or 5.9.6 to mitigate the vulnerability.
Monitor system logs for any suspicious activities related to unauthorized file access.

Long-Term Security Practices

Regularly review and update security configurations to prevent similar vulnerabilities.
Conduct security audits to identify and address any potential security gaps.

Patching and Updates

Apply patches and updates provided by Mattermost promptly to ensure the security of the server and prevent exploitation of this vulnerability.