A security error by Google seems to have re-established access for users that have been previously denied the same to Google Webmaster Tools and Google Analytics. This poses a serious threat to web owners since ex-employees or contractors or consultants that previously had access to these accounts can once again regain access and cause irreparable harm. Users that had been denied access to Webmaster Tools and Analytics due to a variety of reasons can again gain access to such accounts and regain the option to make changes in these accounts. They can easily redirect or de-index URLs, de-index complete websites, or make all changes previously permitted to them. This serious flaw could leave web owners and their SEO teams exposed to some serious damage.
Many web owners discovered to their horror that employees that were denied access to Webmaster Tools for well over a year were suddenly discovered to have become verified owners. Social networking websites such as Twitter are already aflutter with news of this security error.
One ex-SEO director of eBay, Dennis Goedegebuure tried to gain access to his old eBay Webmaster Tools account at eBay and was surprised to learn that he could do so even though he had not worked for the company since the past 15 months.
Google needs to plug this gaping security hole in Webmaster Tools and Analytics quickly before disgruntled ex- employees or unscrupulous ex-members take undue advantage and cause deliberate damage to countless websites.
On your part, you should open your Google Webmaster Tools and Google Analytics account regularly to check if any members or users that have been denied access are now shown as re-verified to access your accounts. You need to again deny access to such users immediately until Google figures out a way to fix the issue.