Computerworld - https://www.computerworld.com/article/3277983/mac-os-x/apple-patches-macs-as-it-starts-retirement-clock-for-el-capitan.html#tk.rss_all
Apple last week released an update for macOS High Sierra, boosting the numeric label to 10.13.5 and simultaneously starting the clock on ending support for 2015’s El Capitan.
Approximately one in eight Mac owners currently runs OS X 10.11, otherwise known by the Yosemite landmark of “El Capitan,” according to analytics vendor Net Applications. Data published June 1 by the metrics firm said that during May El Capitan powered 12.9% of all Macs.
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Apple’s update for 2017’s High Sierra – the already-mentioned 10.13.5 – patched 32 security vulnerabilities, including critical bugs