Mozilla has been alerted that this issue is being actively exploited in the wild. This vulnerability was fixed in Firefox versions 17.0.7 and 22, which were released on June 25, 2013. Users who are on the latest version of Firefox (version 22) or Firefox ESR (version 17.7) are not at risk. Mozilla urges all users to make sure their Firefox is up to date and follow these instructions to confirm they are running the latest Firefox version. We are actively investigating this information and we will provide additional information when it becomes available.”]
Source: https://blog.mozilla.org/security/2013/08/04/investigating-security-vulnerability-report/