Vulnerability identifier: #VU9453

Vulnerability risk: Low

CVSSv3.1: 3.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-17091

CWE-ID: CWE-330

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
WordPress
Web applications / CMS

Vendor: WordPress.ORG

Description
The vulnerability allows a remote attacker to bypass certain security restrictions.

The vulnerability exists in wp-admin/user-new.php script due to usage of a determinate substring in newbloguser key, which can be directly derived from the user ID. A remote attacker can guess the key and bypass intended access restrictions.

Mitigation
Update to version 4.9.1.

Vulnerable software versions

WordPress: 3.7 - 3.7.23, 3.8 - 3.8.23, 3.9 - 3.9.21, 4.0 - 4.0.20, 4.4 - 4.4.13, 4.1 - 4.1.20, 4.2 - 4.2.17, 4.3 - 4.3.13, 4.5 - 4.5.11, 4.6 - 4.6.8, 4.7 - 4.7.7, 4.8 - 4.8.3, 4.9

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External links
http://wordpress.org/news/2017/11/wordpress-4-9-1-security-and-maintenance-release/

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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.