Owners of WordPress-based websites should update the Jetpack plug-in as soon as possible because of a serious flaw that could expose their users to attacks.
Jetpack is a popular plug-in that offers free website optimization, management and security features. It was developed by Automattic, the company behind WordPress.com and the WordPress open-source project, and has over 1 million active installations.
Researchers from Web security firm Sucuri have found a stored cross-site scripting (XSS) vulnerability that affects all Jetpack releases since 2012, starting with version 2.0.