WordPress 4.9.1 security release
Incident Report for Pantheon Operations
Resolved
WordPress.org has released version 4.9.1. This release is classified as a critical 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/2017/11/wordpress-4-9-1-security-and-maintenance-release/
[2] - http://helpdesk.getpantheon.com/customer/portal/articles/361248
Posted Nov 29, 2017 - 15:06 PST