C

The getcpu wrapper function has been added, which returns the currently used CPU and NUMA node.

Optimized generic exp, exp2, log, log2, pow, sinf, cosf, sincosf and tanf.

The reallocarray function is now declared under _DEFAULT_SOURCE, not just for _GNU_SOURCE, to match BSD environments.

The popen and system do not run atfork handlers anymore.

strftime’s default formatting of a locale’s alternative year (%Ey`) has been changed to zero-pad the year to a minimum of two digits, like %y.

As a GNU extension, the _ and - flags can now be applied to %EY to control how the year number is formatted; they have the same effect that they would on %Ey.

The glibc.tune tunable namespace has been renamed to glibc.cpu and the tunable glibc.tune.cpu has been renamed to glibc.cpu.name.

An archaic GNU extension to scanf, under which %as, %aS, and %a[…​] meant to scan a string and allocate space for it with malloc, is now restricted to programs compiled in C89 or C++98 mode with _GNU_SOURCE defined.

CVE-2018-19591

CVE-2019-6488

CVE-2016-10739