The 2.3 series release notes contain important changes in this release series.

Bug Fixes

• Deleting an impersonation OAuth token via the API would fail.

Security Fixes

• Packages have been updated to the latest security versions.

Known Issues

• We incorrectly redirect to the dashboard if you accessed GitHub Enterprise using an alias while in private mode. This might happen if you set a fully qualified domain name but the subdomain resolves correctly.
• Email can't be sent over TLS when SSL is disabled.
• Deleting a user doesn't delete their gists, which can cause problems with replication.
• Images uploaded to issues save with an absolute URL, so they can be broken if the hostname changes.
• On a freshly set up GitHub Enterprise without any users, an attacker could create the first admin user.
• The management console settings interface doesn't clearly show if you have previously uploaded certificate files or a private key.
• Management console sessions can expire too quickly for Safari users.
• Gist repositories are not garbage collected by the maintenance scheduler.
• Custom firewall rules aren't maintained during an upgrade.
• Repositories that are in an incomplete state, which is a rare problem, can cause the migration to the new repository disk layout to fail.
• Enqueued background jobs are sometimes not purged when a repository is deleted.
• When a fork is detached from its repository network by an administrator or by changing visibility, its filesystem path won't be updated on a high availability replica until at least one commit has been pushed.
• Viewing raw files in repositories owned by a user or organization named "github" fails with a 400 error. (updated 2015-12-15)
• Trying to add a file to a repository with Subversion 1.9 clients incorrectly detects the file already exists and fails. (updated 2016-01-14)

Thanks!

The GitHub Team