The MITRE CVE dictionary describes this issue as:
The startDocumentLoad function in browser/base/content/browser.js in Mozilla Firefox 3.5.x before 3.5.11 and 3.6.x before 3.6.7, and SeaMonkey before 2.0.6, does not properly implement the Same Origin Policy in certain circumstances related to the about:blank document and a document that is currently loading, which allows (1) remote web servers to conduct spoofing attacks via vectors involving a 204 (aka No Content) status code, and allows (2) remote attackers to conduct spoofing attacks via vectors involving a window.stop call.
Find out more about CVE-2010-1206 from the
MITRE CVE dictionary dictionary and
The Red Hat Security Response Team has rated this issue as having low
security impact, a future update may address this flaw.