Vulnerability identifier: #VU7181

Vulnerability risk: Medium

CVSSv3.1: 6.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-6921

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Drupal
Web applications / CMS

Vendor: Drupal

Description
The vulnerability allows a remote attacker to bypass security restrictions on the site.

The weakness exists due to improper validation of some fields by the file REST resource when manipulating files. If the site has the RESTful Web Services (rest) module enabled, the file REST resource is enabled and allows PATCH requests and has, a remote attacker can obtain a user account on the site with permissions to upload files and to modify the file resource.

Successful exploitation of the vulnerability results in access bypass.

Mitigation
Update to version 8.3.4.

Vulnerable software versions

Drupal: 8.3.0 - 8.3.3, 8.2.0 - 8.2.8, 8.1.0 - 8.1.10, 8.0 - 8.0.6

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External links
http://www.drupal.org/SA-CORE-2017-003

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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