User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.4) Gecko/20100624 CentOS/3.6-8.el5.centos Firefox/3.6.4 FirePHP/0.4 Build Identifier: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.4) Gecko/20100624 CentOS/3.6-8.el5.centos Firefox/3.6.4 FirePHP/0.4 I discovered that session cookies and sessionStorage in javascript does not clear if the browser is forceably closed (For example by a kill -9 or the like). Reproducible: Always Steps to Reproduce: 1. Open a window set a session cookie, or put some data in the sessionStorage object, 2. Kill the browser (Kill -9) 3. open the window again check cookies or session storage. Actual Results: Session data is still there. Expected Results: It should be cleared

That's because session restore restores everything, including session cookies. That's on purpose, so you can continue what you were doing. For security, it doesn't happen with cookies that are created in https websites. Discussion in bug 530594