Self Cross-site Scripting Vulnerability Identified in Yoast SEO 3.3.2


Advisory by Netsparker (now Invicti)
Name: Self XSS Vulnerability in Yoast SEO 3.3.2
Affected Software: Yoast SEO
Affected Versions: 3.3.2 and possibly below
Vendor Homepage: 
Vulnerability Type: Cross-site Scripting
Severity: Important
Status: Fixed
Invicti Advisory Reference: NS-16-007

Technical Details

Proof of Concept URLs for XSS vulnerabilities in Yoast SEO 3.3.2:

URL: /wordpress/wp-admin/admin-ajax.php
Parameter Name: new_value
Parameter Type: POST
Attack Pattern: ><iMg src=N onerror=alert(9)>

For more information on cross-site scripting vulnerabilities, see Cross-site Scripting (XSS).

Advisory Timeline

29 Jun 2016 – First Contact
01 Jul 2016 – Vendor Replied
27 Jul 2016 – Advisory Released


Patch released by Yoast SEO and announced here.

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.