Advisory by Netsparker.
Name: DOM XSS Vulnerability in Twenty Fifteen WordPress Theme
Affected Software : WordPress
Affected Versions: 4.2.1 and probably below
Vendor Homepage : and
Vulnerability Type : DOM based Cross-site Scripting
Severity : Important
CVE-ID: CVE-2015-3429
Netsparker Advisory Reference : NS-15-007

Technical Details
Proof of Concept URL for DOM XSS in WordPress:<img/src/onerror=alert(123)>

For more information on this vulnerability read DOM Based Cross-site Scripting (XSS).

Advisory Timeline
22/04/2015 - First Contact
07/05/2015 - Vulnerability fixed
07/05/2014 - Advisory released

Download WordPress version 4.2.2 which includes fix for this vulnerability.

Credits & Authors
These issues have been discovered by Omar Kurt while testing Netsparker Web Application Security Scanner.

About Netsparker
Netsparker finds and reports security flaws and vulnerabilities such as SQL Injection and Cross-site Scripting (XSS) in all websites and web applications regardless of the platform and the technology they are built on. Netsparker's unique detection and exploitation techniques allow it to be dead accurate in reporting vulnerabilities, hence it is the first and only False Positive Free web application security scanner.