Microsoft has updated the advisory for MS09-054, a cumulative security update for Internet Explorer, to describe its impact on Firefox users. The first version failed to mention any impact, leading to what may have been an overreaction on Mozilla's part.

An entry on Microsoft's Security Research & Defense blog goes into the matter further. The bottom line: Firefox users should apply MS09-054, even though it's labeled as an update for IE.

After receiving the same clarification from Microsoft, Mozilla has removed the Microsoft code from the blocklist. They are working on a way to allow users to override such blocking in the future. Clearly they got some complaints.