The MITRE CVE dictionary describes this issue as:
Mozilla Firefox 3.0.5 and earlier 3.0.x versions, when designMode is enabled, allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a certain (a) replaceChild or (b) removeChild call, followed by a (1) queryCommandValue, (2) queryCommandState, or (3) queryCommandIndeterm call. NOTE: it was later reported that 3.0.6 and 3.0.7 are also affected.
Find out more about CVE-2009-0071 from the
MITRE CVE dictionary dictionary and
NIST NVD.
Statement
Red Hat does not consider a crash of a client application such as Firefox to be a security issue.