Mozilla Firefox is an open source Web browser.
Several flaws were found in the processing of malformed web content. A web page containing malicious content could cause Firefox to crash or, potentially, execute arbitrary code as the user running Firefox. (CVE-2009-0352, CVE-2009-0353, CVE-2009-0356)
Several flaws were found in the way malformed content was processed. A website containing specially-crafted content could, potentially, trick a Firefox user into surrendering sensitive information. (CVE-2009-0354, CVE-2009-0355)
A flaw was found in the way Firefox treated certain HTTP page caching directives. A local attacker could steal the contents of sensitive pages which the page author did not intend to be cached. (CVE-2009-0358)
For technical details regarding these flaws, please see the Mozilla security advisories for Firefox 3.0.6. You can find a link to the Mozilla advisories in the References section.
All Firefox users should upgrade to these updated packages, which contain Firefox version 3.0.6, which corrects these issues. After installing the update, Firefox must be restarted for the changes to take effect.