Recently, a security researcher released a zero-day stored XSS vulnerability in WordPress, meaning it was previously undisclosed and, at the time, unpatched. The vulnerability affected the latest versions of WordPress at release, including 4.2.
How Can The XSS Vulnerability Be Exploited?
The xss vulnerability involves how WordPress stores comments in its MySQL database. Comments are stored as text and the size of that text is limited to 64 kilobytes, or 64,000 characters. Given a previously approved comment, an attacker could create a malformed comment using approved HTML tags and tack on 64 kb of any character (perl -e ‘print “a” x 64000’). The 64 kb of junk is truncated and what’s left is a malicious comment in the database which will run whenever it’s viewed. And what can run is up to the attacker – creating backdoors, stealing credentials, malicious redirects and more.