Advisory by Netsparker (now Invicti)
Name: XSS Vulnerability in Pligg CMS
Affected Software: Pligg CMS
Affected Versions: 2.0.2 and possibly below
Vendor Homepage:
Vulnerability Type: Cross-site Scripting
Severity: Important
Status: Not fixed
Invicti Advisory Reference: NS-15-011

Technical Details
Proof of Concept URL for XSS in Pligg CMS:

Page: groups.php
Parameter Name: keyword
Parameter Type: GET
Attack Pattern:'+alert(0x000D82)+'

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

Advisory Timeline
13/05/2015 - First Contact
30/06/2015 - Second Contact
16/07/2015 - Third Contact
30/07/2015 - Advisory released

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.