The 2.19 series release notes contain important changes in this release series.

Security Fixes

• HIGH: An improper access control vulnerability was identified in the GitHub Enterprise Server API that allowed an organization member to escalate permissions and gain access to unauthorized repositories within an organization. This vulnerability affected all versions of GitHub Enterprise Server prior to 2.21. We have issued CVE-2020-10516 in response to this issue. The vulnerability was reported via the GitHub Bug Bounty program.
• Packages have been updated to the latest security versions.

Bug Fixes

• Internet-facing GitHub Enterprise Server instances could be indexed by search engines.

Known Issues

• On a freshly set up GitHub Enterprise Server without any users, an attacker could create the first admin user.
• Custom firewall rules are not maintained during an upgrade.
• Git LFS tracked files uploaded through the web interface are incorrectly added directly to the repository.
• Issues cannot be closed if they contain a permalink to a blob in the same repository where the file path is longer than 255 characters.
• When pushing to a gist, an exception could be triggered during the post-receive hook.
• When "Users can search GitHub.com" is enabled with GitHub Connect, issues in private and internal repositories are not included in GitHub.com search results.
• Security alerts are not reported when pushing to a repository on the command line. (updated 2020-06-23)

Thanks!

The GitHub Team