CVE-2021-32655 : What You Need to Know

Nextcloud Server versions prior to 19.0.11, 20.0.10, and 21.0.2 are affected by a vulnerability that allows an attacker to convert a Files Drop link to a federated share. This could lead to privilege escalation issues. The vulnerability is patched in the mentioned versions.

Understanding CVE-2021-32655

This section provides insights into the nature and impact of the CVE-2021-32655 vulnerability.

What is CVE-2021-32655?

CVE-2021-32655 affects Nextcloud Server versions < 19.0.11, >= 20.0.0, < 20.0.10, and >= 21.0.0, < 21.0.2, allowing attackers to manipulate Files Drop links into federated shares, potentially granting unauthorized privileges.

The Impact of CVE-2021-32655

The vulnerability could result in a scenario where users inadvertently grant read privileges to unauthorized parties through manipulated shares, potentially compromising data privacy and security.

Technical Details of CVE-2021-32655

This section outlines the specific technical details of the CVE-2021-32655 vulnerability.

Vulnerability Description

In affected Nextcloud Server versions, the issue arises when a Files Drop link is converted to a federated share, causing unexpected privilege escalations that could compromise data integrity.

Affected Systems and Versions

Nextcloud Server versions < 19.0.11, >= 20.0.0, < 20.0.10, and >= 21.0.0, < 21.0.2 are vulnerable to this issue, potentially impacting users of these versions.

Exploitation Mechanism

Attackers can exploit this vulnerability by converting a Files Drop link to a federated share, manipulating privileges in a way that enables unauthorized access.

Mitigation and Prevention

To address CVE-2021-32655, consider the following mitigation strategies and best security practices.

Immediate Steps to Take

Users should update their Nextcloud Server installations to versions 19.0.11, 20.0.10, or 21.0.2 to mitigate the vulnerability.

Long-Term Security Practices

Regularly monitor for security advisories and apply updates promptly to prevent exploitation of known vulnerabilities.

Patching and Updates

Stay informed about security patches and updates released by Nextcloud to ensure the latest security fixes are applied to the server.