WP Offload SES Lite < 1.4.5 - Stored Cross-Site Scripting (XSS)
The plugin did not escape some of the fields in the Activity page of the admin dashboard, such as the email's id, subject and recipient, which could lead to Stored Cross-Site Scripting issues when an attacker can control any of these fields, like the subject when filling a contact form for example. The XSS will be executed in the context of a logged in admin viewing the Activity tab of the plugin.
Proof of Concept
An attacker must send a message by using a contact form existing on the vulnerable website, and be able to control the subject to set an XSS Payload in it. The payload will be triggered by an administrator having access to the Offload SES dashboard.