Unchecked NULL pointer usage when handling invalid aliases in CopyKeyAliasesToKeymap in xkbcomp/keycodes.c in xkbcommon before 0.8.1 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file.
https://usn.ubuntu.com/3786-2/
https://usn.ubuntu.com/3786-1/
https://security.gentoo.org/glsa/201810-05
https://lists.freedesktop.org/archives/wayland-devel/2018-August/039232.html
https://github.com/xkbcommon/libxkbcommon/commit/badb428e63387140720f22486b3acbd3d738859f