The MITRE CVE dictionary describes this issue as:
Use-after-free vulnerability in ISC BIND 9.3.0 up to 9.3.3, 9.4.0a1 up to 9.4.0a6, 9.4.0b1 up to 9.4.0b4, 9.4.0rc1, and 9.5.0a1 (Bind Forum only) allows remote attackers to cause a denial of service (named daemon crash) via unspecified vectors that cause named to "dereference a freed fetch context."
Find out more about CVE-2007-0493 from the
MITRE CVE dictionary dictionary and
Not vulnerable. This issue did not affect the versions of ISC BIND as shipped with Red Hat Enterprise Linux 2.1, 3, or 4.