xkbcomp -- Several vulnerabilities

X.Org reports:

Multiple issues have been found in xkbcomp that have been previously been published as CVEs in libxbkcommon. libxkbcommon is (to some degree) a fork of xkbcomp and some of the code base is identical. These CVEs were published earlier as:

• CVE-2018-15853: Endless recursion in xkbcomp/expr.c resulting in a crash
• CVE-2018-15859: NULL pointer dereference when parsing invalid atoms in ExprResolveLhs resulting in a crash
• CVE-2018-15861: NULL pointer dereference in ExprResolveLhs resulting in a crash
• CVE-2018-15863: NULL pointer dereference in ResolveStateAndPredicate resulting in a crash

[source]