CVE-2021-41233 : Security Advisory and Response

Nextcloud text is a collaborative document editing tool built for the Nextcloud server. This CVE involves a missing authorization issue in the Nextcloud Text application, potentially allowing attackers to access folder names and requires an upgrade to mitigate the risk.

Understanding CVE-2021-41233

This CVE revolves around a security vulnerability in the Nextcloud Text application, impacting versions of the Nextcloud Server.

What is CVE-2021-41233?

The vulnerability allows attackers to view "File Drop" folder names by exploiting the Nextcloud Text application without proper authorization.

The Impact of CVE-2021-41233

CVSS Base Score: 6.5 (Medium Severity)
Attack Vector: Network
Attack Complexity: Low
Confidentiality Impact: Low
Integrity Impact: Low
Successful exploitation requires knowledge of the sharing link.

Technical Details of CVE-2021-41233

This section delves into the specific technical aspects of the vulnerability.

Vulnerability Description

The issue arises from missing authorization controls in the Nextcloud Text application, leading to unauthorized access to folder names.

Affected Systems and Versions

Nextcloud Server < 20.0.14
Nextcloud Server >= 21.0.0, < 21.0.6
Nextcloud Server >= 22.0.0, < 22.2.1

Exploitation Mechanism

The attacker needs knowledge of the sharing link to exploit the vulnerability successfully.

Mitigation and Prevention

To address CVE-2021-41233, users and administrators can take the following steps:

Immediate Steps to Take

Upgrade Nextcloud Server to versions 20.0.14, 21.0.6, or 22.2.1
Disable the Nextcloud Text application in the application settings if an immediate upgrade is not feasible.

Long-Term Security Practices

Regularly update Nextcloud Server and applications
Implement access control and authorization mechanisms
Educate users on secure sharing practices

Patching and Updates

Stay informed about security advisories and promptly apply patches to mitigate vulnerabilities.