http://nvd.nist.gov/nvd.cfm?cvename=CVE-2007-0981 "Mozilla based browsers allows remote attackers to bypass the same origin policy, steal cookies, and conduct other attacks by writing a URI with a null byte to the hostname (location.hostname) DOM property, due to interactions with DNS resolver code." Seamonkey seems vulnerable. See also https://bugzilla.mozilla.org/show_bug.cgi?id=370445
The SeaMonkey version in Fedora Extras 6 is 1.0.8. SeaMonkey 1.0.8 is based on Mozilla technology version 1.8.0.10. The underlying bug at mozilla.org has been marked as fixed and verified 1.8.0.10 So I conclude this bug has been fixed in seamonkey-1.0.8-0.6.2.fc6 since 2007-03-01.