Users of the 'All in One SEO Pack' plug-in should update as soon as possible, security researchers from Sucuri warn Many WordPress websites could be at risk of compromise if their administrators don’t upgrade a popular search engine optimization (SEO) plug-in to a newly released version that fixes serious vulnerabilities.Researchers from Web security firm Sucuri found two flaws in a plug-in called “All in One SEO Pack” that potentially allow attackers with access to non-administrative WordPress accounts to elevate their privileges and inject malicious code into the administration panel.[ InfoWorld’s expert contributors show you how to secure your Web browsers in a free PDF guide. Download it today! | Learn how to protect your systems with Roger Grimes’ Security Adviser blog and Security Central newsletter, both from InfoWorld. ] “If your site has subscribers, authors and non-admin users logging in to wp-admin, you are a risk,” the Sucuri researchers said Saturday in a blog post. “If you have open registration, you are at risk, so you have to update the plugin now.”The “All in One SEO Pack” plug-in automatically optimizes WordPress content for more efficient indexing by search engine crawlers to achieve a better ranking in search results. According to statistics from the official WordPress add-ons repository, the plug-in has been downloaded over 18.5 million times to date.One of the two flaws discovered by Sucuri can be exploited by a regular user, like an author or a subscriber, to modify a post’s SEO title, description and keyword meta tags created by the plug-in. If used maliciously, this could result in damage to a site’s search result ranking. However, the vulnerability can also be combined with a second flaw to inject malicious JavaScript code on the administrator control panel that would execute when the page is loaded.This means an attacker could potentially do things like change the admin account’s password or insert backdoor code into the website files to conduct other malicious activities at a later time, the Sucuri researchers said.WordPress site administrators are advised to upgrade the “All in One SEO Pack” plug-in to version 2.1.6 which was released Sunday in the WordPress add-ons repository. An update can also be initiated from the plug-in’s administration panel. WordPress sites have been a popular target for attackers over the years and vulnerabilities in the platform’s third-party components such as plug-ins or themes have been exploited in the past.A critical vulnerability found in 2011 in an image resize script called TimThumb that was bundled in many WordPress themes was still being targeted in attacks over a year later. Patch Management SoftwareApplication Security