CVE-2021-32656 Explained : Impact and Mitigation
Learn about CVE-2021-32656, a high-severity vulnerability in Nextcloud Server versions prior to 19.0.11, 20.0.10, and 21.0.2 allowing unauthorized access to user data.
This article provides an overview of CVE-2021-32656, a vulnerability in Nextcloud Server that enables attackers to gain access to user information.
Understanding CVE-2021-32656
CVE-2021-32656 is a security vulnerability in the Nextcloud Server versions prior to 19.0.11, 20.0.10, and 21.0.2 that allows attackers to access user data through federated sharing mechanisms.
What is CVE-2021-32656?
Nextcloud Server is a data storage package that facilitates federated sharing between servers. This CVE exposes a flaw where a malicious actor can exploit a public link to extract user details from a legitimate server.
The Impact of CVE-2021-32656
The vulnerability's impact is rated as HIGH with a CVSS base score of 8.6, posing a significant threat to confidentiality. Attackers can access basic user information due to improper access control in federated sharing functionality.
Technical Details of CVE-2021-32656
The vulnerability stems from Nextcloud's automatic sharing of registered user data with other servers, triggered when the 'Add server automatically once a federated share was created successfully' setting is enabled.
Vulnerability Description
A flaw in federated share mechanisms allows unauthorized access to user data, compromising confidentiality.
Affected Systems and Versions
Nextcloud versions earlier than 19.0.11, 20.0.10, and 21.0.2 are vulnerable to this exploit.
Exploitation Mechanism
Attackers can gain access to user information by manipulating public links in federated sharing.
Mitigation and Prevention
To address CVE-2021-32656, immediate action is necessary to prevent unauthorized access and enhance security measures.
Immediate Steps to Take
Disable the 'Add server automatically once a federated share was created successfully' setting in the Nextcloud configuration as a temporary workaround.
Long-Term Security Practices
Regularly review and update security settings, restrict public link sharing, and monitor for suspicious activities to improve overall system security.
Patching and Updates
Install the latest patches and updates provided by Nextcloud to eliminate the vulnerability and protect user data.