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 3.8.x ranging from 3.8 and up to (and including) 3.8.24 are vulnerable.
Remediation
Update to WordPress version 3.8.25 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 LazyEater Multiple Unspecified Vulnerabilities (1.2.4)
WordPress Plugin Ocean Extra Cross-Site Scripting (2.1.1)
WordPress Plugin HTTP Headers Multiple Vulnerabilities (1.9.1)
PHP Other Vulnerability (CVE-2006-4484)
WordPress Plugin yolink Search for WordPress Cross-Site Scripting (2.5)