Organizations provide multiple web-based services to its users. To manage easy provisioning and deprovisioning of users, they offer single sign-on (SSO) service as an access control mechanism. To access any SSO service, users need to remember only one set of credentials. These credentials are managed by organization’s identity and access management system (IAM). The identity provider (IDP) is the federated identity management platform to authenticate users, for service providers (SPs), to access and use the services. Users may access the services provided by organization via web browsers. Modern web browsers provide a feature called tabbed browsing, where tabs are widgets within the browser window, so that the users can stay organized when browsing multiple Web sites. In this paper, we analyzed how SSO works in a tabbed browsing environment. Our analysis shows that, in some scenarios, a user may not sign out from some services that he or she was using. This situation may lead to information security attacks. Also, we propose a solution that can be implemented on the browser to ensure a safe sign-out process.