github "Action Required - SSH Key Vulnerability"に対処する方法

3/8 githubからセキュリティに関する次のようなメールが届きました。超訳すると、こんな感じです。

A security vulnerability was recently discovered that made it possible for an attacker to add new SSH keys to arbitrary GitHub user accounts. This would have provided an attacker with clone/pull access to repositories with read permissions, and clone/pull/push access to repositories with write permissions. As of 5:53 PM UTC on Sunday, March 4th the vulnerability no longer exists.

3/4 標準時間 5:53にはこの脆弱性はなくなりました。

# Required Action
Since you have one or more SSH keys associated with your GitHub account you must visit to approve each valid SSH key.