Resolved - WordPress.org has released version 4.9.7. This release is classified as a security release for all previous versions of WordPress.[1] Pantheon has made the update available for one-click update in site dashboards. We urge all users to update all environments as soon as possible. Instructions for applying core updates can be found in our Support Center.[2]

[1] - https://wordpress.org/news/2018/07/wordpress-4-9-7-security-and-maintenance-release/
[2] - http://helpdesk.getpantheon.com/customer/portal/articles/361248
Jul 5, 11:12 PDT