Security Advisory

Edit permission check not enforced on WebDAV COPY action (NC-SA-2016-004)

19th July 2016

Risk level: Medium

CVSS v3 Base Score: 3.1 (AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N)

CWE: Permission Issues (CWE-275)

HackerOne report: 145950

Description

The WebDAV endpoint was not properly checking the permission on a WebDAV "COPY" action. This allowed an authenticated attacker with access to a read-only share to put new files in there. It was not possible to modify existing files.

Affected Software

• Nextcloud Server < 9.0.52 (CVE-2016-9461)
• server/3491400261c1454a9a30d3ec96969573330120cc

Action Taken

The permission check is now also performed on "COPY" actions,

Resolution

It is recommended that all instances are upgraded to Nextcloud 9.0.52.

Acknowledgements

The Nextcloud team thanks the following people for their research and responsible disclosure of the above advisory:

• Kumar Saurabh - Vulnerability discovery and disclosure.

This advisory is licensed CC BY-SA 4.0.