Description
WordPress is prone to a cross-domain Flash injection vulnerability. An attacker may leverage this issue to execute arbitrary script code in the browser of an unsuspecting user in the context of the affected site, allowing the attacker to steal cookie-based authentication credentials, or to fool a user into inserting credentials on a fake Flash form. WordPress versions 4.8.x ranging from 4.8 and up to (and including) 4.8.4 are vulnerable.
Remediation
Update to WordPress version 4.8.5 or latest
References
https://opnsec.com/2017/10/cve-2016-9263-unpatched-xsf-vulnerability-in-wordpress/
https://opnsec.com/2017/10/flashme-wordpress-vulnerability-disclosure-cve-2016-9263/
Related Vulnerabilities
Oracle JRE CVE-2013-2407 Vulnerability (CVE-2013-2407)
WordPress Plugin Frontier Post Security Bypass (1.3.2)
Drupal Permissions, Privileges, and Access Controls Vulnerability (CVE-2014-5267)
WordPress Plugin User Meta Manager Multiple Vulnerabilities (3.4.6)
WordPress Plugin WordPress Download Manager Cross-Site Scripting (3.2.15)