CVE-2023-2808 : Security Advisory and Response

This CVE-2023-2808 involves a vulnerability in Mattermost that allows an attacker to trigger a link preview on a disallowed domain using a specially crafted link due to the failure to normalize UTF confusable characters when generating a hyperlink preview.

Understanding CVE-2023-2808

This section delves into the specifics of CVE-2023-2808, its impact, technical details, affected systems, exploitation mechanism, and mitigation strategies.

What is CVE-2023-2808?

CVE-2023-2808 is a vulnerability in Mattermost that arises from the platform's inability to normalize UTF confusable characters when determining whether a link preview should be generated. This oversight enables malicious actors to trigger a link preview on disallowed domains by manipulating the link.

The Impact of CVE-2023-2808

The impact of CVE-2023-2808 is classified as having a base severity level of "MEDIUM" with a CVSS V3.1 base score of 4.3. The vulnerability poses a risk to the integrity of affected systems as attackers can exploit it to render previews for domains that should be disallowed.

Technical Details of CVE-2023-2808

This section provides detailed information about the vulnerability, including the description, affected systems and versions, and the exploitation mechanism.

Vulnerability Description

Mattermost fails to properly normalize UTF confusable characters when deciding whether to generate a hyperlink preview. This weakness can be exploited by threat actors to trigger a link preview on prohibited domains using a specially crafted link.

Affected Systems and Versions

The versions of Mattermost affected by CVE-2023-2808 include those less than 7.1.9, 7.8.4, and 7.9.3. Versions 7.1.9, 7.8.4, 7.9.3, and 7.10 are identified as unaffected by this vulnerability.

Exploitation Mechanism

By leveraging the lack of URL normalization in Mattermost, attackers can manipulate UTF confusable characters within hyperlinks to provoke link previews on restricted domains, thereby circumventing security measures.

Mitigation and Prevention

In response to CVE-2023-2808, it is crucial to implement immediate steps to mitigate risks, adopt long-term security practices, and prioritize patching and updates.

Immediate Steps to Take

Update Mattermost to version 7.1.9, 7.8.4, 7.9.3, 7.10, or newer to address the vulnerability and prevent malicious exploitation of the lack of URL normalization issue.

Long-Term Security Practices

Enhance security practices by regularly monitoring and updating systems, conducting security audits, and educating staff on cybersecurity best practices to prevent similar vulnerabilities in the future.

Patching and Updates

Stay vigilant for security updates from Mattermost and promptly apply patches as they are released to strengthen the platform's security posture and safeguard against potential cyber threats.