CVE-2023-28643 : Security Advisory and Response

This CVE involves a potential share collision for recipients when caching is enabled in Nextcloud Server, impacting certain versions of the software.

Understanding CVE-2023-28643

This vulnerability in Nextcloud Server could allow a recipient to experience issues when receiving 2 shares with the same name while a memory cache is configured. The second share might replace the first one instead of being properly renamed, leading to potential data confusion for users.

What is CVE-2023-28643?

CVE-2023-28643 specifically affects users of Nextcloud Server, which is an open-source home cloud implementation. The vulnerability stems from the incorrect handling of shared folders with the same name, causing potential conflicts for recipients.

The Impact of CVE-2023-28643

The impact of this CVE is considered medium, with a base severity score of 5.5. While the attack complexity is low and user interaction is required, the confidentiality, integrity, and availability impacts are rated as low.

Technical Details of CVE-2023-20657

In this section, we will delve into the specific technical aspects of the vulnerability, including its description, affected systems, and how exploitation can occur.

Vulnerability Description

The vulnerability arises from the mishandling of shared folders with identical names, leading to potential data collision issues for recipients in Nextcloud Server.

Affected Systems and Versions

Users of Nextcloud Server versions below 24.0.9 and between 25.0.0 and 25.0.3 are affected by this vulnerability. It is crucial for users to upgrade their Nextcloud Server to version 25.0.3 or 24.0.9 to mitigate the risk.

Exploitation Mechanism

Exploiting this vulnerability requires the existence of two shared folders with the same name being sent to a recipient while a memory cache is in use. The caching mechanism leads to the second share replacing the first one, potentially causing confusion and data integrity issues.

Mitigation and Prevention

To address the risks associated with CVE-2023-28643, immediate steps need to be taken by affected users while also implementing long-term security practices to prevent similar vulnerabilities from impacting systems in the future.

Immediate Steps to Take

Users are advised to upgrade their Nextcloud Server to version 25.0.3 or 24.0.9 as soon as possible to eliminate the vulnerability. For users unable to upgrade immediately, it is recommended to avoid sharing two folders with the same name to the same recipient to mitigate the risk.

Long-Term Security Practices

In addition to immediate upgrades, implementing strong access controls, regular security assessments, and staying informed about software updates and security advisories can help enhance the overall security posture of systems running Nextcloud Server.

Patching and Updates

Regularly checking for software updates, patches, and security advisories from Nextcloud can ensure that the latest security fixes are applied promptly to safeguard against known vulnerabilities like CVE-2023-28643.