Chrome for Windows and all modern versions of Firefox are known to be safe. However, even if your browser is safe, certain third-party software, including some anti-virus products and adware programs, can expose you to the attack by intercepting TLS connections from the browser. If you are using a safe browser but our client test says you’re vulnerable, this is a likely cause.
If you're curious, your client currently offers the following cipher suites:
Here are some additional tool for developers debugging their applications. You can try our low-level state-machine tests by loading this page and this page. (If either connection succeeds, your software is vulnerable.) Additionally, you can see what cipher suites your TLS library offers by loading this page. (If the list includes any EXPORT ciphers, your software is vulnerable.)