I just received an email from support@github.com (see below). Is this real or a hoax?

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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.

While no known malicious activity has been reported, we are taking additional precautions by forcing an audit of all existing SSH keys.

# Required Action

Since you have one or more SSH keys associated with your GitHub account you must visit https://github.com/settings/ssh/audit to approve each valid SSH key.

Until you have approved your SSH keys, you will be unable to clone/pull/push your repositories over SSH.

# Status

We take security seriously and recognize this never should have happened. In addition to a full code audit, we have taken the following measures to enhance the security of your account:

- We are forcing an audit of all existing SSH keys - Adding a new SSH key will now prompt for your password - We will now email you any time a new SSH key is added to your account - You now have access to a log of account changes in your Account Settings page

Sincerely, The GitHub Team

--- https://github.com support@github.com