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 4.2.x ranging from 4.2 and up to (and including) 4.2.18 are vulnerable.
Remediation
Update to WordPress version 4.2.19 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
WordPress Plugin WP Google Maps Cross-Site Scripting (7.10.41)
WordPress Plugin CM Pop-Up banners for WordPress Cross-Site Scripting (1.4.10)
WordPress Plugin WP Mega Menu Security Bypass (1.3.9)
Joomla Improper Access Control Vulnerability (CVE-2016-9838)
WordPress Plugin WP-OliveCart Multiple Vulnerabilities (3.1.2)