An updated thunderbird package that fixes one security issue is nowavailable for Red Hat Enterprise Linux 5 and 6.The Red Hat Security Response Team has rated this update as havingimportant security impact. A Common Vulnerability Scoring System base score, which gives a detailed severity rating, is available from theCVE link in the References section. Mozilla Thunderbird is a standalone mail and newsgroup client.A flaw was found in the processing of malformed content. Malicious contentcould cause Thunderbird to crash or execute arbitrary code with theprivileges of the user running Thunderbird. Red Hat would like to thank the Mozilla project for reporting this issue.Upstream acknowledges VUPEN Security via the TippingPoint Zero DayInitiative project as the original reporter.Note: This issue cannot be exploited by a specially-crafted HTML mailmessage as JavaScript is disabled by default for mail messages. It couldbe exploited another way in Thunderbird, for example, when viewing the fullremote content of an RSS feed.All Thunderbird users should upgrade to this updated package, whichcorrects this issue. After installing the update, Thunderbird must berestarted for the changes to take effect.