Serious Chrome zero-day
The reason that even the Chrome team are wading in with you’d-better-update warnings is the recent appearance of a zero-day security vulnerability, dubbed CVE-2019-5786, for which Google says it is “aware of of reports that an exploit […] exists in the wild.” A vulnerability, or vuln for short, is a bug that makes software go wrong in a way that reduces computer security. Precise information about the Chrome CVE-2019-5786 zero-day is hard to come by at the moment – as Google says:
Access to bug details and links may be kept restricted until a majority of users are updated with a fix.
Source: nakedsecurity.sophos.com