SB2017040509 - Incorrect permission assignment for critical resource in Nextcloud Server

Description

This security bulletin contains information about 1 security vulnerability.

1) Incorrect permission assignment for critical resource (CVE-ID: CVE-2017-0883)

The vulnerability allows a remote authenticated user to read and manipulate data.

Nextcloud Server before 9.0.55 and 10.0.2 suffers from a permission increase on re-sharing via OCS API issue. A permission related issue within the OCS sharing API allowed an authenticated adversary to reshare shared files with an increasing permission set. This may allow an attacker to edit files in a share despite having only a 'read' permission set. Note that this only affects folders and files that the adversary has at least read-only permissions for.

Remediation

Install update from vendor's website.

References

• https://hackerone.com/reports/169680
• https://nextcloud.com/security/advisory/?id=nc-sa-2017-001