A  vulnerability in the Slimstat WordPress plugin could allow a malicious user to inject arbitrary JavasScript code on the plugin access log functionality.

The plugin allows users to gather data analytics for the WordPress site and will track certain information such as the browser and operating system details, plus page visits to optimize the website analytics.

The cross-site-scripting vulnerability, XXS, allows the attacker to forge an analytics request by pretending his browser has a specially crafted plugin to inject arbitrary code on the plugin access log, according to a May 21 Sucuri blog post.

Those using the vulnerable plugin have been instructed to update their systems as soon as possible.