#VU31432 Improper access control in Nextcloud Server - CVE-2016-9461

Vulnerability identifier: #VU31432

Vulnerability risk: Low

CVSSv4.0: 1.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2016-9461

CWE-ID: CWE-284

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Nextcloud Server
Client/Desktop applications / Messaging software

Vendor: Nextcloud

Description

The vulnerability allows a remote authenticated user to manipulate data.

Nextcloud Server before 9.0.52 & ownCloud Server before 9.0.4 are not properly verifying edit check permissions on WebDAV copy actions. 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.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Nextcloud Server: 9.0.0 - 9.0.51

---

External links
https://www.securityfocus.com/bid/97276
https://github.com/nextcloud/server/commit/3491400261c1454a9a30d3ec96969573330120cc
https://github.com/owncloud/core/commit/0622e635d97cb17c5e1363e370bb8268cc3d2547
https://github.com/owncloud/core/commit/121a3304a0c37ccda0e1b63ddc528cba9121a36e
https://github.com/owncloud/core/commit/acbbadb71ceee7f01da347f7dcd519beda78cc47
https://github.com/owncloud/core/commit/c0a4b7b3f38ad2eaf506484b3b92ec678cb021c9
https://hackerone.com/reports/145950
https://nextcloud.com/security/advisory/?id=nc-sa-2016-004
https://owncloud.org/security/advisory/?id=oc-sa-2016-014

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.