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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

Action Taken

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

Acknowledgements

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


This advisory is licensed CC BY-SA 4.0.