CVE Vulnerabilities

CVE-2023-39962

Improper Access Control

Published: Aug 10, 2023 | Modified: Aug 16, 2023
CVSS 3.x
7.7
HIGH
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
CVSS 2.x
RedHat/V2
RedHat/V3
Ubuntu

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 19.0.0 and prior to versions 19.0.13.10, 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.8, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1, a malicious user could delete any personal or global external storage, making them inaccessible for everyone else as well. Nextcloud server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 19.0.13.10, 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.9, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. As a workaround, disable app files_external. This also makes the external storage inaccessible but retains the configurations until a patched version has been deployed.

Weakness

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

Affected Software

Name Vendor Start Version End Version
Nextcloud_server Nextcloud 19.0.0 (including) 19.0.13.10 (excluding)
Nextcloud_server Nextcloud 20.0.0 (including) 20.0.14.15 (excluding)
Nextcloud_server Nextcloud 21.0.0 (including) 21.0.9.13 (excluding)
Nextcloud_server Nextcloud 22.0.0 (including) 22.2.10.14 (excluding)
Nextcloud_server Nextcloud 23.0.0 (including) 23.0.12.9 (excluding)
Nextcloud_server Nextcloud 24.0.0 (including) 24.0.12.5 (excluding)
Nextcloud_server Nextcloud 25.0.0 (including) 25.0.9 (excluding)
Nextcloud_server Nextcloud 26.0.0 (including) 26.0.4 (excluding)
Nextcloud_server Nextcloud 27.0.0 (including) 27.0.0 (including)

Extended Description

Access control involves the use of several protection mechanisms such as:

When any mechanism is not applied or otherwise fails, attackers can compromise the security of the product by gaining privileges, reading sensitive information, executing commands, evading detection, etc. There are two distinct behaviors that can introduce access control weaknesses:

Potential Mitigations

  • Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
  • Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

References