Sep 2, 21:41 PDT
Resolved – PHP.net has released version 7.0.23. This release is classified as a security release . Pantheon has deployed this PHP version platform-wide. The release addresses a vulnerability that could allow for arbitrary code execution, MS-ISAC 2017-076 .
Drupal 7 sites on PHP 7.0 that haven’t updated core in a few months will encounter a new PHP notice dumped to the screen on non-live environments, which can be fixed by updating to Drupal 7.55 or later, or by applying this patch  from drupal.org issue 2877243 . The notice is suppressed in Live environments.
 – http://php.net/ChangeLog-7.php#7.0.23
 – https://www.cisecurity.org/advisory/multiple-vulnerabilities-in-php-could-allow-for-arbitrary-code-execution-14/
 – https://www.drupal.org/files/issues/DATE_RFC7231-2877243-1.patch
 – https://www.drupal.org/node/2877243