> In particular, we discovered that it was fixed on May 21, 2013 (between the releases of glibc-2.17 and glibc-2.18)
Gentoo is listing glibc version 2.19-r1 as the latest stable version [2] and is using that per default.
[1] http://www.openwall.com/lists/oss-security/2015/01/27/9
[2] http://packages.gentoo.org/package/sys-libs/glibc