Description
WordPress Plugin Postie is prone to multiple vulnerabilities, including cross-site scripting and security bypass. Exploiting these issues could allow an attacker to execute arbitrary script code in the browser of an unsuspecting user in the context of the affected site, to steal cookie-based authentication credentials, or to perform otherwise restricted actions and subsequently publish posts by spoofing the From information of an email message. WordPress Plugin Postie version 1.9.40 is vulnerable; prior versions may also be affected.
Remediation
Disable the plugin until a fix is available
References
https://github.com/V1n1v131r4/Exploiting-Postie-WordPress-Plugin-/blob/master/README.md
https://packetstormsecurity.com/files/155973/WordPress-Postie-1.9.40-Cross-Site-Scripting.html